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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.