The intense yellow colored complexes of Ti(IV) and N-pyridy1-N′-β-naphthylthiourea are extractable into isoamyl alcohol. The spectrophotometric studies following Job's and molar ratio methods have shown that 1:2 and 1:3 (meta1:ligand) complexes predominate in the acidity ranges of 2.5–6 and 7–9.5NHCl, respectively. The values of the stability constants, sepwise and overall, have been calculated following extended Leden's, Yatsimirskii's, and Harvey-Manning's methods. The analytical suitability of the reagent for microdetermination of titanium has also been investigated.