Department of Chemistry, University of Delhi, Delhi-110 007 Manuscript received 2 January 1979. revised 5 June 1979, accepted 6 October 1979 Salicylaldebyde hydrazone (SH) has been recommended as a chromogenic reagent for the spectrophotometric determination of palladium(lI) and osmium(VIII) in presence of each other and several other diverse ions. SH forms 1:2 and 1:1 complexes with palladium and osmium respectively. The complexes show maximum absorbance at 425 nm and 430 am in the \(p\)H ranges 3.0 to 5.0 and 9.5 to 10.0 respec­tively. The colour systems obey Beer's law upto 21 ppm and 19 7 ppm respectively. The sensitivites of the colour reactions are 0.02 µg/cm2 and 0.06 µg/cm' for palladium and osmium respectively.