In order to investigate the thermoelectric properties of Zn{k}In2O{3+k} homologous compounds, the samples of Zn{k}In2O{3+k} (k = integer between 1 and 9) were prepared by calcining the mixed powders of ZnO and In2O3 followed by sintering at 1823 K for 2 hours in air, and their electrical conductivities and Seebeck coefficients were measured as a function of temperature in the range of 500 K to 1150 K. X-ray diffraction analysis of the sintered samples clarified that single-phase specimens were obtained for Zn{k}In2O{3+k} with k = 3, 4, 5, 7, 8, 9. Electrical conductivity of the Zn{k}In2O{3+k} decreased with increasing temperature, and decreased with increasing k for k \geq3. The Seebeck coefficient was negative at all the temperatures for all compositions,confirming that Zn{k}In2O{3+k} is an n-type semiconductor. Absolute values of the Seebeck coefficient increased linearly with increasing temperature and increased with increasing k for k \geq3. Thetemperature dependence of the Seebeck coefficient indicated that Zn{k}In2O{3+k} could be treated as an extrinsic degenerate semiconductor. Figure-of-merits of Zn{k}In2O{3+k} were evaluated from the measured electrical conductivity and Seebeck coefficient, and the reported thermal conductivity. Zn7In2O10 has the largest figure-of-merit overall the temperatures, and its highest value was 1.5{\times}10 ^{-4} K^{-1}$ at 1145 K.5 K.