Abstract Polarographie study of rhodium(III) in thiocyanate media. Application to the microanalysis of organometallic compounds. Reduction of rhodium(III) at the dropping mercury electrode is performed in thiocyanate media by classical a.c. and pulse polarography, and linear sweep voltammetry. The reduction ( E 1 2 = —0.5 V vs. SCE) is shown to be a 3e irreversible transfer. Coulometric investigation confirms this result and rhodium gives a dark grey deposit at the mercury surface. This explains the i—t curves even in the presence of gelatin as maximum suppressor and the anomalous slope of log [ i/( i d - i)] at potentials more cathodic than the E 1 2 value. A.c. and differential pulse polarography are suitable for analysis down to the 0.1-ppm level. Palladium and platinum do not interfere although there is enhancement of the base line, but ruthenium affects the end of the polarogram, probably because of catalytic hydrogen evolution. Applications to organometallic compounds and industrial catalytic bimetallic grids show good agreement with the predicted compositions.