Visible-light-responsive ZnO/NiO/In2O3 mixed metal oxide (ZNI-MMO) photoelectrocatalysts with different Ni/In molar ratios were derived from corresponding ternary hydrotalcite-like precursors followed by calcination at 600 degrees C. The as-obtained samples were characterized by XRD, TGA, BET, XPS, SEM, TEM, and UV-vis spectra techniques. The optimal molar ratio of Ni/In was found to be 1:1, where the sample (ZNI-1-MMO) was formed by the aggregation of nanospheres with an average diameter of about 50 nm and a BET specific surface area of 33.80 m(2)/g. With a 1.5 V bias potential, the ZNI-1-MMO photoelectrode exhibited high photoelectrocatalytic activity toward methylene blue (MB) degradation. The photoelectrocatalytic degradation of MB followed pseudo-first-order kinetics. Radical trapping experiments were conducted to probe the reactive species in the degradation processes. Results indicated that h(+) and (OH)-O-center dot may be responsible for the efficient MB removal. The photoelectrodegradation mechanism of MB by ZNI-1-MMO-1.5 V photoelectrode was also discussed.