By replacing absolute ethanol, water was used as a ubiquitous and low-cost solvent to dissolve metal nitrates and organic additives to obtain a precursor solution that showed long-term stability and reproducibility. This precursor solution was used to deposit a CuMn₂O₄ ceramic film on a stainless steel substrate using the convenient and inexpensive sol-gel dip-coating technique. The X-ray diffraction (XRD) profile of the ceramic film annealed for 1 h at 450 °C was found to coincide with that of crystalline CuMn₂O₄ in the JCPDS database. The CuMn₂O₄ ceramic film obtained at an annealing temperature of 500 °C exhibited excellent solar absorptance (α_s=0.905) and thermal emittance (ε₁₀₀=0.120). By optimizing the deposition parameters, we systematically investigated the effect of the chemical components, surface texture, and thickness of the ceramic film on its optical properties. Subjected to a thermal stability test at 252 °C, the CuMn₂O₄ ceramic film showed good thermal stability with performance criterion (PC) values below 0.05.