At 75, Bridget Riley is still in the pink with colourful new works

Though she won fame in the psychedelic Sixties, the artist Bridget Riley is best known for working in simple black and white. But there is nothing monochrome about her latest works, which go on display for the first time this week.

Having celebrated her 75th birthday six weeks ago, Riley is about to reveal a new taste for shocking salmon pinks and purples. The new paintings, the first since her retrospective at Tate Britain three years ago, will go on display at the Timothy Taylor Gallery in central London.

Never prolific, Riley has produced around half a dozen giant pieces in the past couple of years, of which four or five - the details are to be finalised today - are expected to go on display.

"They're very exciting," Mr Taylor said. "They're certainly as successful as anything she has ever made. There is strong museum interest internationally and also a very strong local client base.

"She doesn't make that much. These take a great deal of time. It's an important exhibition for people to come to, as it's not often you get to see this calibre of painting."

Though the artist is expected at her formal opening tomorrow, before the show opens to the public on Wednesday, she has declined all interviews.

But Mr Taylor said: "She's fantastically well. She looks well and relaxed and you can see how well she's painting."

Riley was born in London in 1931 and studied art at Goldsmith's College and later the Royal College of Art where her contemporaries included Peter Blake and Joe Tilson.

In the Fifties and Sixties, her black-and-white paintings - the work for which she is probably best known today - established her as the leading figure of what was called the Op Art movement.

By the end of the 1960s, she was using colour, though not always the dynamic counterpoint of vivid tones on display this week.

She has been exhibited at all the major British galleries including the Hayward, the Serpentine and Tate, as well as overseas.

Today, she divides her time between London and France but also has a studio in Cornwall.

The price of the works has not been disclosed. "It would embarrass Bridget," said Mr Taylor. But an indication of her market value can be seen at the auction houses.

An early monochrome work, Untitled (Diagonal Curve) 1966, will be offered at Sotheby's on 21 June, where it is expected to make up to £400,000.

Oliver Barker, the head of the auction house's contemporary art department, said it was possibly the finest work by Riley ever to appear at auction and was certainly the most important piece of the period to come on the open market.

"It is a particularly happy coincidence that the painting is being auctioned at a time when a group of Riley's recent works is being shown at one of London's leading contemporary art galleries," he said.

Untitled (Diagonal Curve) was the culmination of her work in black and white and was one of the last of her monochrome works before she began to experiment with colour the following year.

A world record price for a Bridget Riley was set at Sotheby's earlier this year when Persephone I sold for £467,200.

Bridget Riley: New Paintings and Gouaches is at the Timothy Taylor Gallery, 24, Dering Street, W1 from Wednesday until 15 July