Electrocatalysts for the oxygen reduction reaction (ORR) has been developed to meet the requirements for renewable energy applications. Herein, we explore mixed valence transition-metal oxides with a spinel structure for this purpose. A simple and scalable method was employed for synthesis of four different types of spinel oxide nanocrystals (NiCo2O4, NiMn2O4, ZnCo2O4, and ZnMn2O4). This allowed for a systematic investigation of the influence of the composition of the catalysts (XY2O4, X=Ni, Zn and Y=Co, Mn) on ORR. Given the general spinel structure of XY2O4, we changed X (Ni, Zn) and Y (Co, Mo) systematically. The influence of different transition-metals on the morphology and electrocatalytic properties of the spinel oxides toward ORR were studied and compared using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron microscopy, and voltammetry. In general, cobalt-based spinel oxides exhibited significant electrocatalytic activity towards the ORR, with Ni-substituted spinel oxides outperforming their respective Zn-substituted congeners. These findings may have profound impact in the research field of renewable energy.