A few cobalt substituted barium stannate, BaSn1-xCoxO3 compositions have been synthesized by solid state ceramic method. Seebeck coefficient alpha has been measured as a function of temperature. Positive values of 'alpha' indicate that holes are the majority charge carriers. AC conductivity, sigma (ac) has been measured in the temperature range 310-550 K and frequency range 100 Hz to 10c MHz. The contributions of the grains and grainboundaries to the total conductivity have been obtained by complex plane impedance analysis. Complex plane impedance analysis shows that conduction occurs by hopping of charge carriers among localized sites.