CdTe0:9Se0:1:Cl crystals doped with chlorine at 5 x 10(17) cm(-3) level were grown by the vertical Bridgman method. The composition of Se throughout the ingot was nearly constant at x = 0.110+/-0.016. The electrical resistivity of CdTeSe:Cl was 4.5 x 10(9)Omega cm. Chemical etchants were employed to obtain stoichiometric and flat surfaces for electrode deposition, and the effects of the etchants on CdTeSe surfaces were analyzed by photoluminescence (PL) and AFM with different bromine concentrations and etching times. The mobility-lifetime products of electron and hole in CdTeSe:Cl crystals were of the order of similar to 10(-2) cm(2)/V and its values are greater than those for CdTe crystals. The energy resolution of a CdTeSe:Cl detector was tested using a Am-241 radioactive source. (C) 2007 Elsevier B.V. All rights reserved.