In this work, chemical bath deposition (CBD) of US was monitored using a quartz crystal microbalance as a function of time, temperature, reactant concentration (ex situ atomic absorption measurement), and pH level. It is found that the reaction could be limited by mass transport at certain concentrations and temperatures. The measurements also indicate the total Cd concentration in the solution changes dramatically in the linear growth regime with a constant deposition rate. One possible explanation is that the linear growth regime is actually a combination of molecule-by-molecule growth and cluster-by-cluster growth mode. This hypothesis is further supported by real time dynamic light scattering and transmission electron microscopy measurements. (C) 2004 The Electrochemical Society.