Nanocrystalline anatase titanium dioxide powders were produced by a hydrothermal synthesis route in pure form and substituted with trivalent Ga³⁺ and Y³⁺ or pentavalent Nb⁵⁺ with the intention of creating acceptor or donor states, respectively. The electrical conductivity of each powder was measured using the powder-solution-composite (PSC) method. The conductivity increased with the addition of Nb⁵⁺ from 3 × 10⁻³ S/cm to 10 × 10⁻³ S/cm in as-prepared powders, and from 0.3 × 10⁻³ S/cm to 0.9 × 10⁻³ S/cm in heat-treated powders (520°C, 1 h). In contrast, substitution with Ga³⁺ and Y³⁺ had no measureable effect on the material's conductivity. The lack of change with the addition of Ga³⁺ and Y³⁺, and relatively small increase upon Nb⁵⁺ addition is attributed to ionic compensation owing to the highly oxidizing nature of hydrothermal synthesis.