Hollow nanocages composed of heterostructures play an important role in oxygen evolution reaction (OER) due to their high electrocatalytic activity induced by the interfacial polarization within the interface of the heterostructure. In this work, ZIF-67 was used to synthesize Co₃O₄/CoMoO₄ hollow nanocages (Co₃O₄/CoMoO₄ HNC). Transmission electron microscopy (TEM) images verify that Co₃O₄/CoMoO₄ HNC was composed of Co₃O₄/CoMoO₄ heterostructures. X-ray photoelectron spectroscopic (XPS) characterizations show that the Mo 3d peaks of Co₃O₄/CoMoO₄ are located at lower binding energy compared with CoMoO₄, indicating charge transfer between Co₃O₄ and CoMoO₄. The electrochemical studies show that Co₃O₄/CoMoO₄ HNC exhibited excellent OER activity in an alkaline medium with only 248 mV overpotential required to achieve a current density of 10 mA cm⁻². Co₃O₄/CoMoO₄ HNC was tested as the anode material in a homemade water-splitting device to produce oxygen. The Co₃O₄/CoMoO₄ HNC‖20 % Pt/C electrolytic cell shows equivalent performance to RuO₂‖20 % Pt/C cell at 50 °C. The excellent OER performance of Co₃O₄/CoMoO₄ HNC is attributed to the interfacial charge transfer between Co₃O₄ and CoMoO₄ which promote the adsorption of OH⁻. Besides, the hollow nanocage structures provide a large surface area, leading to more active sites for OER.