Some time in early July an extraordinary aluminium building like a cloud of smoke or a splashing raindrop will appear in a wooded corner of Hyde Park.

With a roof that swoops low enough to be used as a table or an arm rest at one end, it will hover outside the Serpentine Gallery until October when it will be sold to the highest bidder and dismantled.

This is the vision for the 10th summer pavilion commissioned by the gallery.

It was in 2000 that the Serpentine’s director Julia Peyton-Jones unveiled a groundbreaking new concept: to invite a leading architect who has yet to complete a building in England to create a temporary summer pavilion next to the gallery.

Since then the Serpentine pavilion has become a spectacular mainstay of the London artworld’s year. Each summer (apart from 2004 when there was a cock-up and MVRDV’s design went unrealised) and with varying success, a new weird and wonderful temporary structure takes up residence in one of the city’s greenest spaces hosting debates, parties, lectures, film screenings and one-off events as well as providing a haven for early morning joggers, a cafe for buggy-pushing mothers and a bar for late night drinkers.

A maximum of six months from invitation to completion is the goal and the projects are self funding. Each pavilion is paid for by sponsorship (with the identity of the chief sponsor, Netjets, reflecting the Serpentine’s appeal to the European super-rich who have colonised the contemporary art market in recent years), sponsorship in kind and the eventual sale of the pavilion.

Zaha Hadid was first to pick up the gauntlet and the list of those who have followed her includes a who’s who of international brand-name architects: Daniel Libeskind, Toyo Ito, Oscar Niemeyer, Rem Koolhaas and, last year, the most famous and in-demand of them all: Frank Gehry.

The architects of this year’s structure are not quite as well known outside the profession, at least in this country.

SANAA is the practise of the Japanese architects Kazuyo Sejima and Ryue Nishizawa, who together won the Golden Lion at the Venice Architecture Biennale in 2004.

Their buildings include a satellite of the Louvre in Lens, France, the New Museum of Contemporary Art in New York and distinctive shops for the fashion designers Dior, Prada and Issey Miyake.

“Sanaa’s buildings have a lightness of touch,” Ms Peyton-Jones said yesterday.

“This one will give you a sense of the sky being on top of your head. The height of the roof varies significantly from 1m to 3.5m and was conceived by the architects so that people can use it as a table. It creates a very dynamic structure which is wonderfully reflective.”

The architects said that they were aiming to fashion a pavilion from “floating aluminium, drifting freely between the trees like smoke. The reflective canopy undulates across the site, expanding the park and sky.”

Although there will be some walls, it will appear to be see-through, allowing uninterrupted views across the park and its sinuous shape will wrap around the surrounding trees. That much the architects can control, though it appears they still have a little to learn about the British weather.

The pavilion, they say, will be “a sheltered extension of the park where people can read, relax and enjoy lovely summer days.”

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