<p>Hydrogen peroxide (H₂O₂) serves as an eco-friendly intermediate in environmental applications and is crucial in biochemical metabolism in humans. However, the overproduction and accumulation of excessive H₂O₂ can be detrimental to the human body, leading to significant cellular damage. Consequently, the CdS/NiS immobilized reduced graphene oxide (CdS/NiS/rGO) nanozyme was synthesized to facilitate the oxidation of 3, 3, 5, 5-tetramethylbenzidine (TMB) into a blue-colored product (TMBox) in the presence of H₂O₂. From the experimental findings, an effective and economical colorimetric approach for the detection of H₂O₂ has been developed. This method demonstrated a sensitive response to H₂O₂ concentrations ranging from 0.1 to 100 mM with linear range from 0.1 to 10 mM, exhibiting good recovery (95.33-103.33%) in real sample analysis, with lowest limit of H₂O₂ detected at 0.1 mM. CdS/NiS/rGO nanozyme is found reusable up to four cycles without significantly diminishing the activity, shows good storage stability till three weeks, and selective to H₂O₂. This study offers a practical method for environmental monitoring, biosensing, and additional applications.</p> Graphical abstract <p></p>