In this work, we report the properties of chemically deposited US thin films in a cadmium-sodium citrate system. This chemical bath deposition process does not employ ammonia. We deposited four series of films at different cadmium content in the chemical bath process and determined their properties. The obtained information can be very useful for the optimization of the deposition process in order to reduce the amount of toxic chemical waste, mainly Cd-containing waste. The structural and optical properties of the US films were determined from X-ray diffraction, optical transmission and reflection spectroscopy and scanning electron microscopy measurements. We found that the properties of the films are very sensitive to the amount of cadmium in the deposition process. The process allows the deposition of good quality US thin films using 1.12, 0.84 and 0.76 mg of cadmium per milliliter of reaction solution. (C) 2003 Elsevier B.V. All rights reserved.