Multiwalled carbon nanotubes (MWNTs) supported and unsupported bimetallic zinc and manganese oxides nanoparticles (Zn-Mn NPs) were synthesized by wet chemical precipitation method. Zn-Mn and MWNTs/Zn-Mn oxides NPs were used as photocatalysts for the photodegradation of malachite green in aqueous medium under UV irradiation. The photodegradation study of malachite green was carried out by UV/vis spectrophotometer. The Mn-Zn and MWNTs/Mn-Zn oxides NPs degraded about 93% and 96% of dye, respectively, within 2 h of irradiation time. Effect of several parameters like time, pH, catalyst dosage and concentration of dye on the photocatalytic degradation was studied. The optimum conditions were obtained at pH 9 (93% dye degraded in 1.5 h), at 0.0435 g of catalyst (76.04% of dye degraded in 1 h), at 12.5 ppm dye concentration (88.41% dye degraded in 45 min). The activity of recovered catalyst was also examined.