Scientists have taken the first step toward creating a simple cream that could one day treat skin cancer.

Researchers at Melbourne's RMIT University have designed a new chemical that acts like a known virus by killing off melanoma cells.

While the chemical is effective at destroying the cancer cells, normal skin cells remain unharmed.

Dr Taghrid Istivan said the preliminary research will hopefully lead to developing a cream to treat early stage melanoma.

"We found it is active against cancer cells, against melanoma, but it doesn't harm the normal cells," she said.