The present invention relates to a process for the preparation of antioxidant activity rich extracts from tuberous roots of Decalepis hamiltonii and the use of said extract as anti-oxidant, free radical scavenger, the extract is having an anti-oxidant activity in the range of 4 to 47% and also it can serve as better antioxidant since it can prevent more than one type of free radicals unlike other synthetic antioxidants which can quench only one type of radical.