We report the synthesis and characterization of the antimony-doped oxypnictide superconductor,LaO0.8F0.2FeAs1−xSbx (x = 0.05 and 0.10). The parent compound LaOFeAs with fluorine dopingexhibits superconductivity at the maximum transition temperature∼28.5 K (at ambient pressure). Here we partially substitute As by Sb(LaO0.8F0.2FeAs1−xSbx) and observe enhancement of the transition temperature to 30.1 K. This is one rare case whereTc increases with doping in the conducting layer (FeAs) and this leads to the highesttransition temperature in any La-based oxypnictide. X-ray diffraction and energy-dispersivex-ray analysis measurements confirm the phase purity of the samples and the presence ofSb. The magneto-resistance measurements show that the value of the upper critical fieldHc2(0) is about 73 T, corresponding to a coherence length(ξGL) of 22 Å. The Seebeck coefficient measurements indicate electron transport with a strongcontribution from electron–electron correlation. These results provide interestinginsight into the origin of superconductivity in this novel series of compounds.