Manganites based oxides have shown promises recently for the applications as n-type thermoelectric materials. In the presnt work, Environment friendly, non-toxic perovskite Gd1-xSrxMnO3 (x = 0.5,0.6,0.7,0.8) ceramics were prepared by conventional solid state reaction route.The samples were then examined for their crystal structure (single phase) and morphology by XRD and SEM, respectively. Rietveld refinement of the XRD data of these manganites revealed orthorhombic crystal structure. Electrical conductivity(σ) and Seebeck coefficient (S) were measured in the wide range of temperature from room temperature to 900 K.Negative thermo-power (S) values obtained in these ceramics confirmed the n-type behavior of these manganites. Temerature dependent conductivity measurement showed the signature of metal to semiconductor (M-S) transitions in these samples. Furthermore,the conductivity mechanism of these manganites were explained using variable range hopping and small polaron hopping model.