© 2014, National Institute R and D of Materials Physics. All rights reserved. CdIn2S4 powder was synthesized by a simple hydrothermal method employing L-cysteine as a sulfur source. Effects of pH of the solution, holding time and reaction temperature on purity, crystallinity and microstructure of the products were investigated. The products were characterized by XRD and FTIR, indicating pure CdIn2S4 with a cubic spinel structure at 240 °C for 48 h with the initial pH (1.8). Based on FESEM and TEM observations, the CdIn2S4 was an octahedral shape with an average size of 200-250 nm. EDX spectrum showed the existences of Cd, In and S elements with the atomic ratio of 1.00:2.06:3.95. The optical band gap of the CdIn2S4 was 2.30 eV. It can be seen that pH, holding time and reaction temperature were the important factors for the synthesis of the pure CdIn2S4 powders. Increase in pH yielded impurity in the products which could be explained by the hard and soft acid base (HSAB) concept. Increase in the length of the holding time could not improve the purity; however, a greater numbers of particles with well-structured octahedrons could be observed. A larger particle sizes with good crystalline structure were provided when high temperatures were used.