Oxypnictides of types CeOFeAs1 − xSbx, CeO0.9F0.1FeAs1 − xSbx and CeO0.8F0.2FeAs1 − xSbx have been synthesized in order to understand the effective change in electron doping by the twin effectsof F − incorporation and the variation in Fe–As bonding by substitution of a larger ion (Sb) at the Assite. All the compounds crystallize in a tetragonal ZrCuSiAs-type structure (space group:P4/nmm). Both the latticeparameters (a and c) increase with the increase in antimony substitution due to the larger ionic size of antimony.CeOFeAs1 − xSbx (x = 0.1, 0.2and 0.3) compounds were found to be semimetallic, like the parent CeOFeAs. Substitution of Sb inCeOFeAs1 − xSbx resultsin a shift of the temperature of the resistance anomaly corresponding to the structural phase transition.CeO0.9F0.1FeAs1 − xSbx (‘x’ = 0, 0.05, 0.1 and 0.15) was superconducting with a maximum transmission temperature (Tc) of 43.17 K for‘x’ = 0.1, which is higher thanthe antimony-free CeO0.9F0.1FeAs (Tc = 38 K). Further increasein antimony (x > 0.15) results in the suppression of superconductivity. Similarly, Sb doping in optimally electron dopedCeO0.8F0.2FeAs superconductor leads to the lowering of the superconducting transition temperature (‘x’ = 0.1) and further increase in antimony substitution (‘x’ > 0.1) leads to a loss ofsuperconductivity. CeO0.8F0.2FeAs0.9Sb0.1 shows a very high value of the upper critical fieldHc2(0) (137 T) as comparedto Sb-free CeO0.8F0.2FeAs. In this paper, we discuss the first example among electron-doped oxypnictide superconductors wherethe Tc increases as a result of a decrease in chemical pressure (an increase in lattice parameters).