Chemical Bath Deposition (CBD) was used to grow CdS1-xfSexf (x(f) = 0.5) thin films on Corning glass substrates at 75 degrees C. The atomic composition of the bath was varied until an x(f) of 0.5 was obtained, maintaining the deposition time at 120 min. Then the deposition time was modified from 5 to 360 min. The structural and optical properties of the films were analyzed by Scanning Electron Microscopy, Energy Dispersive Spectroscopy, X-Ray Diffraction, UV-Vis Spectroscopy, Profilometry and Inductive Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). A bath atomic composition of Cd:S:Se equal to 0.76:0.55:0.45 was employed to obtain a film of x(f) = 0.5. The films are constituted by clusters of semi-spherical nanoparticles (phi(av) = 15 nm), which are well-arranged in a "nanoworm" structure. The nucleation time of the particles is lower than 5 min. All the films are polycrystalline with hexagonal phase and preferentially orientated on the (002) plane. The crystal size (11-6 nm) and the band gap (2.17 -1.99 eV) decrease with the content of Se and remain constant with the deposition time. The composition x(f) = 0.5 is achieved at different times to the heterogeneous (60 min) and homogeneous reactions (15 min). The kinetics of deposition and the consumption rate of Se change in a similar way, reaching the stability after 60 min. (C) 2015 Elsevier B.V. All rights reserved.