Through this work, we have elucidated the mechanism of hydroxyl radicals (OH •) generation and its life time measurements in biosolution. We observed that plasma-initiated ultraviolet (UV) photolysis were responsible for the continues generation of OH • species, that resulted in OH • to be major reactive species (RS) in the solution. The density and lifetime of OH • species acted inversely proportional to each other with increasing depth inside the solution. The cause of increased lifetime of OH • inside the solution is predicted using theoretical and semiempirical calculations. Further, to predict the mechanism of conversion of hydroxide ion (OH −) to OH • or H 2O 2 (hydrogen peroxide) and electron, we determined the current inside the solution of different pH. Additionally, we have investigated the critical criterion for OH • interaction on cancer cell inducing apoptosis under effective OH • exposure time. These studies are innovative in the field of plasma chemistry and medicine.