The study of the Zn-2x(CuIn)(1-x)S-2 (0 <= x <= 1) solid solutions formation by hydrothermal synthesis using ethylenediaminetetraacetic acid (H4EDTA) as a complexant and surfactant agent is reported for the first time. Different synthesis parameters were varied: the H(4)EDTA concentration, the initial pH value, the Tu concentration, the duration and temperature of autoclaving process. The as obtained powders were characterized by X-ray powder diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and UV/vis/NIR diffuse reflection spectroscopy (DRS). The XRD and EDX results show that, with a careful adjustment of the reaction conditions, especially of the H(4)EDTA concentration and initial pH value of the precursor solution, a mixture of solid solutions with sphalerite type structure can be obtained, which transforms into a single phase solid solution after heat treatment. The particles, as revealed by SEM investigations, have nanoporous hexagonal microplates morphology, about 1 mu m thick and several microns in diameter. The Cu0.159In0.111Zn1.778S2 photocatalyst obtained by this method presents photocatalytic activity for hydrogen evolution from aqueous solutions containing S2- ions as sacrificial agent, even without cocatalyst. Copyright (c) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.