Abstract : The Cu2ZnSnS4 (CZTS) thin films have been electrochemically deposited from a weak acidic medium (pH 4.50~5.00) onto Mo coated and ITO coated glass substrate by using single step electrodeposition method. Tri-sodium citrate was used as a complexing agent. The effect of annealing atmospheres such as Ar, N2, N2+H2S on the structural, morphological, compositional and optical properties of CZTS thin films has been investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and optical absorption techniques respectively. XRD studies reveal that the as-deposited CZTS film is amorphous in nature. Upon annealing in different atmospheres, a relatively more intense and sharper diffraction peaks (112), (200), (220) and (312) of kesterite crystal structure with uniform and densely packed surface morphology is observed in N2+H2S atmosphere. Absorption study shows the band gap energy of as-deposited CZTS thin films is 2.7 eV where as after annealing in various atmospheres, it is found in the range of 1.50 to 1.55 eV.