In this paper, we report a Re(I) complex of Re(CO)3(Cl-PYO)Br, where Cl-PYO stands for 2-(4-chlorophenyl)-5-(pyridin-2-yl)-1,3,4-oxadiazole, including its synthesis, identification, molecular structure, theoretical calculation and photophysical character. Re(CO)3(Cl-PYO)Br is found to be a yellow emitter with long excited state lifetime in pure N2 atmosphere. Theoretical calculation result suggests that this emission comes from a triplet metal-to-ligand-charge-transfer excited state. By doping Re(CO)3(Cl-PYO)Br into a polymer supporting matrix of poly(vinylpyrrolidone), the emission of the resulted composite materials is found to be sensitive towards various oxygen concentrations. The maximum sensitivity is obtained to be 7.88. Owing to the porous structure of fibrous poly(vinylpyrrolidone) matrix, a short response time of 11s towards molecular oxygen is also realized with high photostability.