The reaction pathway of n-butane selective oxidation to maleic anhydride (MA) over vanadium phosphorous oxide (VO)2P2O7 catalysts was systematically probed using in situ transient Diffuse Reflectance Infrared Fourier-Transform Spectroscopy (DRIFTS) in high temperature/high pressure chamber. The unsaturated and saturated noncyclic carbonyl species were determined to be intermediates in n-butane selective oxidation to MA. Furan was detected on the surface of the (VO)2P2O7 catalysts in 1-butene, 1,3-butadiene selective oxidation. It was deduced that furan ring was cleaved to form unsaturated noncyclic carbonyl species before its conversion to MA. Based on these results and in comparison with the literature, a simplified scheme of the reaction network structure can be proposed for n-butane selective oxidation to maleic anhydride.