•Nickel selenide and nickel seleno-sulfide nanostructures were prepared.•Used as an electrocatalyst for the oxygen evolution reaction.•Variations in the OER performance with different Se/S mass ratios were observed.•Short synthesis time and catalytic stability are complimented. Driven by industrial progress and technology expansions, the search for alternative energy resources has been an avenue of present-day research. Herein, we report the synthesis of nickel selenide (NiSe) supported by three-dimensional conducting nickel foam (NF) as a substrate via hydrothermal process for a short duration of only two-hours. Further, the addition of selenium (Se) and sulfur (S) in different ratios during the synthesis, resulted in the formation of well-ordered nickel seleno-sulfide (NiSeS/NF) nanostructures. Electron microscopy analysis revealed a unique hexagonal nanorod morphology of NiSeS grew on top of the NF, whereas NiSe/NF revealed the flake-like structures. The oxygen evolution reaction (OER) performance of these samples were studied in an alkaline (1 M KOH) environment. The addition of ‘S’ significantly enhanced the OER performance of NiSe/NF and the variation of OER performance with respect to different Se/S ratios was studied. The Se/S ratio of 0.75:0.25 delivered the best performance with a two-fold increase in overall current density with respect to NiSe/NF. At last, this work also shed light on formation of oxyanions and the conceivable mechanism after prolonged electrolysis. Display omitted