Neutron reflectivity (NR) and X-ray reflectivity (XRR) were used to determine the structure and composition of trivalent chromium process (TCP) films on aluminum alloy AA-2024. Two deposition methods were developed: immersion and electroassisted (EA) deposition. The EA deposition method was designed to guarantee a well-defined film with a uniform structure and minimum contamination from Al and additives in the precursor solution. Quantitative NR and XRR analysis of the EA-TCP film confirmed linear growth as a function of deposition time. By analyzing both NR and XRR data on as-prepared and dried films, the film composition was determined to be Cr2O3 center dot iH(2)O center dot x(ZrO2 center dot jH(2)O) (i = 2.10 +/- 0.55, j = 1.60 +/- 0.45, and x = 0.85 +/- 0.14).