Highly transparent crystalline CuMnS thin films were deposited on the glass substrate by uncomplicated and low-cost chemical bath deposition (CBD) method at different bath temperatures (50-90 °C). The structural, optical, electrical properties of as-synthesized CuMnS thin films have been investigated. The effect of bath temperature on the structure and morphological properties of CuMnS thin films had determined using XRD, SEM, and EDAX analyses. The prepared thin films at 50 °C and 90 °C consisted entirely of nanocrystalline CuS/MnS composite and CuMnS solid solution, respectively, with hexagonal structure. The results confirm that the crystallite size increased with increasing the bath temperature due to the incorporation of Cu species in the MnS lattice. Copper-manganese sulfide thin films have lesser particle sizes at different bath temperature as shown in SEM images. However, it shows spherical and rod-like structure with little agglomeration. EDAX analysis indicates that the deposited thin films contain Cu, Mn, and S ions without any impurities confirming their purity. UV-Vis-NIR, spectral, and electrical DC measurements were carried out to describe the optical and electrical characteristics of the as-synthesized thin films. UV-Visible spectroscopy shows red shift in the optical band gap with different bath temperatures. The electrical conductivity of different films with increasing the temperature from 298 to 473 K was determined. However, the increment in the bath temperature resulted in an increase in the conductivity of films. This increase could be credited to the film density and shadowing effects. The as-deposited films can be predictable to be useful in sunscreens, solar cells, and electro-optical devices.