Ionic Liquids (ILs) are already recognized by the chemical industry as they possess a wide spectrum of physical and chemical properties (solubility, polarity, viscosity or solvent miscibility). However, a release of ILs from industrial processes into aquatic environments may lead to water pollution, because of their high solubilities in water. Due to these reasons, this work is conducted to investigate the photodegradation on ILs structure varies in alkyl chain length and anion group. The photocatalytic degradation was conducted based on fixed parameter optimized which includes pH = 6, photocatalyst = 1g/L, ILo = 0.11 mM and H2O2 = 0.75 ml/L. The reaction for emimCl follows zero order whereas both bmimCl and bmimBF4 follow the first order reaction. © Published under licence by IOP Publishing Ltd.