Electrochemiluminescence (ECL) of luminol and electrocatalysis by Prussian blue were compared for the selective detection of H2O2 at the boron-doped diamond (BDD) electrodes. The H2O2 detection was optimized by various parameters such as the applied potential at pH 7.4, which is a physiological value usually used for H2O2 detection in enzymatic reactions. At an optimum applied potential of +0.5 V, a linear increase in the ECL signals (R2 = 0.99) was achieved for H2O2 concentrations ranging between 0 to 100 μM with an estimated limit of detection (LOD) of 2.59 μM. This LOD was better than that obtained with electrocatalysis measurements using the same electrode modified with Prussian blue. Furthermore, the interference study in the presence of glucose, Fe3+, Cl−, Ca2+, CO32−, Na+, and F− ions showed a comparable selectivity of the luminol ECL and PB-BDD electrochemical current. Nevertheless, the ECL method exhibited significant advantage in the high stability of its signal response. © 2025 The Royal Society of Chemistry.