The electrodeposition of triangular microstructures of Bi on indium tin oxide surfaces is carried out by optimizing the potentials, precursor concentrations and deposition times. The potential-controlled hierarchical evolution of Bi geometries from triangles to dendrites is demonstrated and the structures have been characterized using SEM, TEM, AFM, XRD, UV-visible absorption and FT-Raman spectroscopy. The Scharifker-Hills model is employed to elucidate the nucleation-growth mechanism of triangular Bi particles. The efficacy of triangular bismuth structures towards the oxidation of H2O2 is analyzed using cyclic voltammetry and electrochemical impedance spectroscopy. By using differential pulse voltammetry and chronoamperometry, indium tin oxide coated with Bi triangles is shown to be a satisfactory sensor for H2O2. © The Royal Society of Chemistry 2016.