AbstractSingle crystals of MoSe2 and rhenium‐doped MoSe2 have been grown by direct vapour transport technique and characterized by optical and electrochemical studies. The transmission spectra show the crystals of MoSe2 and rhenium‐doped MoSe2 to be direct band gap semiconductors with band gap 1.6 eV and 1.2 eV, respectively. Mott‐Schottky plots have been drawn to determine the type of semiconductor and its parameters, Nd, EC and EV.