One-pot synthesis of nanosized CZTS particles using ultrasound employing citric acid as the complexing agent has been studied. The CZTS nanoparticles synthesis at different bath temperatures, pH and power densities was attempted. The power density used for the reaction did not alter the crystallinity and morphology of the synthesized particles. However, the chemical composition and the bandgap of the particles showed significant variation with the applied power density. Apart from affecting the composition, bandgap and electrical characteristics, the bath temperature considerably affected the crystallinity of the CZTS nanoparticles. Based on the conditions of synthesis, the particle size ranged between 25 nm and 40 nm. Depending on the process conditions, the bandgap of the particles varied between 1.4 eV and 2.9 eV. The samples synthesized under a power density of 46 W L−1 and 40 °C bath temperature with reactant pH of 3.5 showed composition closer to the required stoichiometry.