The aim of this study is to investigate the performance of solar photo-catalyst of titanium oxide (TiO2/Solar) process to treat rainwater. The polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in rainwater were chosen to be investigated in this study. The rainwater characterization results revealed that PAHs (NAP, FLT, and PYR) were more predominant in industrial and urban residential areas, whereas OCPs (LIN and DDT) were found to contaminate more on the agricultural and rural residential areas. Central composite design with response surface methodology was used to evaluate the relationships between operating variables for TiO2 dosage, pH, and and initial concentration to identify the optimum operating conditions. Quadratic models for FLT, PYR, LIN, and DDT prove to be significant with low probabilities (<0.0001). The obtained optimum conditions included pH (7), TiO2 concentration (1.54 g/L), and initial concentration (125 µg/L). The maximum removal rates were for FLT (88%), PYR (90%), LIN (66%), and DDT (79%). The polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) removal rates correspond well with the predicted models. The photo-degradation process of FLT, PYR, LIN, and DDT followed pseudo first order rate of reaction through L-H kinetic model. The proposed treatment process achieved higher degradation efficiencies for FLT, PYR, LIN, and DDT.