Thiosalicylamide has been employed for the gravimetric and spectrophotometric determination of platinum. In highly acidic medium, thiosalicylamide reacts with platinum(IV) to form a complex of molecular formula Pt[C 7H 6ONS) 2, 2(C 7H 7ONS)]Cl 2. In acetate medium Pt(C 7H 6ONS) 2 is precipitated. Both complexes are thermally stable and can be weighed directly after drying. Platinum can be determined with thiosalicylamide in presence of Co, Ni, Mn, Zn, Cd, Cr 3+, Th, U 6+, Mo 6+, Rh 3+ or Ir 4+ ions from highly acidic medium. Interference of Fe 3+, V 5+, Os 6+ or Os 8+ is avoided by prior reduction. In acetate medium platinum can be precipitated without interference from appreciable amounts of Fe 3+,Al 3+,Ga 3+, In 3+, Tl 3+ Co, Ni,Mn 2+, Zn, W 6+, Mo 6+ or U 6+ with tartrate as masking agent. Copper and titanium are masked by adding EDTA and fluorides, respectively. Osmium(VI) and osmium(VIII) do not interfere after reduction to osmium(IV) with sulphur dioxide. For spectrophotometric measurements the orange yellow complex formed by platinum(IV) with thiosalicylamide is extracted with chloroform from 3–4.5 M hydrochloric acid solution. The chloroform extract shows maximum absorbance at 430 nm ; Beer's law is obeyed over the range 2.8–9.18 μg Pt ml −1. The molar absorptivity is 1.23·10 3. There are few interferences.