In this work, an in situ chemical reaction deposition technique using solid cadmium precursor films as reaction source and ammonium sulfide-based solutions as anionic reaction medium was presented to deposit uniform, crack-free, densely packed nano-crystalline, hexagonal wurzite structure Cadmium sulfide (CdS) thin films. Influence of the Cd:S molar concentrations in separate cationic and anionic precursor solutions, deposition cycle numbers, and annealing treatment in Ar atmosphere on structure, morphology, film growth, chemical composition, and optical properties of the in situ chemical deposited films are investigated based on XRD, FESEM, AFM, HRTEM, EDS, SAED, and UV–Vis measurements.