The company hopes to launch on the stock market in February and raise £20m to further grow the business.
Redx, which is focused on developing drugs to fight cancer and infectious diseases, has secured three commercial contracts and two collaborations in the past 18 months. This includes an agreement with AstraZeneca UK in August 2014 to develop drugs to combat tumours.
It has also agreed a partnership with the NHS.
A further 13 programmes are in the pipeline and money raised would be used to progress the current developments and add more. It would also fund a third therapeutic subsidiary focused on immunology, supported by grant funding from the Regional Growth Fund.
Neil Murray, chief executive of Redx, said: "The placing and admission to AIM is another important milestone in Redx's development. It will strengthen the business and support our objectives of progressing our programmes and achieving early profitability."