Iron molybdate was prepared via simple solution chemistry method and the photocatalytic degradation of a pesticide (endosulfan) was investigated under visible light irradiation. As-prepared (Fe 2 (MoO 4 ) 3 ) was characterized using scanning electron microscope (SEM), x-ray diffraction (XRD), energy dispersive x-ray spectra (EDX), diffused reflectance spectroscopy (DRS) and Zeta particle sizer techniques. The iron molybdate crystallite size was 36 nm, while grain size was in the range of 160-340 nm. The particles of polymetallic compound were spherical, highly porous and with fluffy texture indicating high surface area. DRS revealed Fe 2 (MoO 4 ) 3 was active under visible region since band gap value calculated was 2.7 eV. Response surface methodology (RSM) was employed for the optimization of photocatalytic activity (PCA) of Fe 2 (MoO 4 ) 3 as a function of catalyst dose, H 2 O 2 dose, solution pH and concentration of endosulfan and up to 77% degradation was achieved at optimum conditions, which was monitored by UV/vis spectroscopy. In response to endosulfan degradation, the chemical oxygen demand (COD) and total organic carbon (TOC) were reduced up to 76% and 67%, respectively. Results revealed that iron molybdate is highly efficient photocatalyst for the degradation of endosulfan under solar light irradiation and could possibly be used for the treatment of endosulfan containing wastewater.