An Oxford scientist whose first wife died from cancer is giving his shares in a new research company to a charity fighting the disease.

Prof Graham Richards is part of the team which has launched Inhibox, an Oxford University spin-off firm providing computer software designed to hunt down cancer-fighting molecules.

Although the program has the potential to make millions of pounds, he has given his shares to the US-based National Foundation for Cancer Research, which has funded much of his work since 1982.

Prof Richards, chairman of Oxford University Chemistry Department, made the decision because his first wife Jessamy died from the disease, aged 42, in 1988.

His second wife Mary, 55, has also undergone surgery for breast cancer.

He said: "When Jessamy died, it was a distressing time for the whole family and I had two young teenage boys who had to go through it.

"Finding a cure is close to my heart and when we found that Mary had breast cancer it was more than a shock. It does look like that she's been cured early on, but she still had cancer."

Research has shown that office workers use about one-fifth of their computer power and Prof Richards has been using a method of utilising that spare energy.

Inhibox produces a computer screensaver, which helps scientists search for cancer-fighting molecules while PCs are left idle, sending the information back to a central database.

PC users download software which picks up a molecule from the database every time the computer is idle. It looks at its molecular structure on the computer screen to see if it has any cancer-fighting properties.

It would have taken one computer decades to trawl through 250 million molecules. The software was designed to speed up the process.

It has already proved successful and 1.2m PC users have downloaded the software from the Internet -- including people from 209 countries -- working the equivalent of 70,000 years of computer time.

Prof Richards and his team have increased the project to cover 3.5 billion molecules.

He said: "I am overwhelmed by the kindness of people in supporting this scheme. About 2,000 people a day are joining. Anyone can access the website at www.chem.ox.ac.uk where there is also a chatroom at which people can exchange views."

The money-making possibilities of the new company lie in its potential to sell information about cancer-fighting molecules to drug companies.

Prof Richards said he was not a "complete saint" and had also handed over his stake in a bid to persuade people to use the software.

He said: "A lot of people won't take part because they do not want to help big pharmaceutical firms, which will make drugs from our findings.

"By making sure that Oxford University and the National Foundation for Cancer Research profit, we know that it will be ploughed back into cancer research."

Prof Richards said he had decided to donate his shares in recognition of the help from ordinary people who have downloaded the program and thereby helped to hunt down useful molecules.

Inhibox was set up by Isis Innovation, a transfer technology company wholly owned by Oxford University, which has the job of commercially exploiting academics' research and ideas.

Inhibox is the first Oxford University spin-off company to be set up under an agreement with merchant bank Beeson Gregory. Under the 15-year agreement the bank is entitled to half the shareholding due to the University in any spin-off firm that exploits ideas invented in the Chemistry department.

The bank gained this right in return for contributing £20m towards the University's new Chemistry laboratories in Parks Road.

Executives at Isis Innovation say that they will shortly announce another chemistry spin-off company that they are now establishing with the help of Beeson Gregory.