He is the golden boy of the art world. And it’s easy to see why. It’s right there on the surface of his shimmering confections. We slip into the opulent world of the artist Gustav Klimt like Hollywood movie stars slip into satin dressing-gowns. No wonder his pictures have become commonplace as posters. And yet, what do we know about Klimt the man?

Very little, is the answer. For while Klimt undoubtedly counts as a celebrity A-list artist, he had absolutely no interest in the cult of personality. “I am quite sure that as a person I am not particularly interesting,” he insisted. “There is nothing special about me. I am a painter who paints day after day from morning to night. Whoever wants to know something about me ought to look carefully at my pictures.”

Now, at last, we can do this. Later this month, Tate Liverpool will present this country’s first comprehensive show of Klimt’s work. It will be a glittering spectacle. But what can the works add to our meagre knowledge of the artist himself?

Klimt was born in 1862 in a suburb of Vienna, the capital of the Austro-Hungarian empire in which, despite occasional trips abroad and summers spent by mountain lakes, he was to remain all his life. He was the second of the seven children (three boys and four girls) of an impoverished immigrant gold-engraver from Bohemia and his wife who, having longed to be a musical performer, encouraged the artistic dreams of her offspring.

“At Christmas there wasn’t even bread, let alone presents,” one of the Klimt girls later recalled, and little Gustav often had to stay at home because he had no trousers. The memory of this poverty remained with him all his life. But, just as reality is transformed by the Midas touch of his paintings, it was transmuted by his own into something more glamorous. Klimt, believing that the hoarding of capital was a source of economic misery, would spend liberally. He paid his models generously and bought lavish presents of robes and jewels for his many ladies.

He was a bright boy, but without money to pay for school his education was mostly practical. At 14, he enrolled in Vienna’s School of Applied Arts. His brother followed him a year later and together they teamed up with a friend, Franz Matsch, in 1879, to form the artists’ company through which he was to come to recognition as a painter of public murals.

The forthcoming show will follow his career on from there, looking at his great and sometimes scandalous decorative cycles, and his appointment as the first president of the innovative Vienna Secession (a movement stylistically allied to Art Nouveau), which, founded in 1897, fought free of stuffy tradition. It moves on through his so-called “golden phase” when, inspired by trips to Venice and by the Byzantine glint of Ravenna’s basilica, he started to create the wonderful mosaic-style pieces that transformed the Viennese bourgeoisie into seductive beauties.

It is hardly surprising that people started to wonder what went on in his studio. Eroticism was barely made decent by his allegorical veils. Klimt may not have looked much like a Lothario. He was a stocky, rather chubby, man with “the cheerful brusque manners of a boy,” recalled the director of the Kunsthalle. But his studio was clearly a factory for lascivious fantasies where compliant models laid themselves bare to the artist’s brush. Nothing was taboo for the artist, who drew anything from copulating couples through masturbating women to homosexual love. Though Klimt never married or had his own home (he lived with his mother and two sisters), he made an incalculable number of conquests, ranging from the prostitutes whom he paid to sit for him to the wives of the patrons he cuckolded even as they paid him to paint.

On the surface, Klimt complied with respectable tradition. He was a creature of habit. When in Vienna, he would walk to the same café every morning, where he would take breakfast, read the papers and write postcards before taking a cab to his studio. There he worked uninterruptedly – drawing for several hours a day. He was obsessed with his health, working out with dumb-bells or throwing the discus with male models. And he was a terrible hypochondriac, nurturing among his many imaginary diseases a fear of the madness that he believed he would inherit from his mother, who suffered from depression. In the evenings he would break his loner’s routine, sometimes to meet Egon Schiele, an artist who was imprisoned for painting his stark pornographic fantasies, but with whom Klimt was to remain a lifelong friend. Klimt was an enormous influence on Schiele’s work, as he was on that of Oskar Kokoschka and other Secessionists.

In the few surviving photographs of him, Klimt, more often than not, seems to be floating around flowerbeds in the open sandals and flowing robes espoused by the Wiener Werkstätte (Viennese Workshops), a crafts organisation formed to provide an alternative to shoddy mass production. One woman recalled that his body exuded a peculiar, almost animal odour.

He was exceptionally animal-like, she insisted. And she was probably right. This was the man who fathered as many as 14 children by several different women, who had a tempestuously passionate affair with Alma Schindler (who went on to marry Mahler), and who kept a studio full of cats whose urine, he swore, made a perfect fixative for his drawings.

Klimt’s most valued companion was a woman called Emilie Flöge. The two passed indolent summers together on lakeside holidays, and shared intellectual discussions around café tables. Flöge was Klimt’s muse and companion. He wrote to her sometimes as often as eight times a day, and the 400 postcards that survive are one of the most important records of an artist who wasn’t really interested in recording either personal details or painting methods. And yet nobody even knows whether Flöge was simply a friend or whether the pair had once been lovers.

Klimt – perhaps hardly surprisingly – contracted syphilis. In retrospect, it has been suggested that this explained his obsession with his health. Some say that the increasingly voyeuristic erotic drawings of his later age can be explained by the impotence caused by his illness, that he was satisfying his lusts in the only way that he now could.

In January 1918, Klimt suffered a stroke. He lay on the bed, his afflicted hand limp and useless. “Do you know what annoys me most of all?” he told a nephew. “That I have to be taken care of by women’s hands while I lie helpless.” He died a month later of influenza.

But he left behind a legacy in the form of the femmes fatales that he laid down upon his canvases, drifting luxuriously upon their beds of gold. These shimmering lovelies speak of a fundamental – and characteristically modernist – clash between an impassioned individual and the traditional society in which he grows up. And it is precisely this tension that makes them so entrancing, that lends his pictures their timeless allure.

Gustav Klimt: Painting, Design and Modern Life in Vienna 1900, Tate Liverpool, Albert Dock, Liverpool (www.tate.org.uk/liverpool 0151-702 7400), May 30-Aug 31 2008

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