The application of cordierite glass-ceramics as electronic materials has been studied extensively because of their excellent dielectric properties. In this study, stoichiometric and P2O5-doped cordierite powders were synthesized by sol-gel method. The effect of P2O5 additive on the crystallization and phase tansformation was investigated using differential thermal analysis (DTA), infrared spectroscopy (IR) and X-ray diffraction (XRD. The activation energies for mu -cordierite to alpha -cordierite transition with various additive concentrations were obtained using Kissinger equation. It was found that P2O5 promotes the mu -cordierite to cr-cordierite transition at low additive concentrations, while it plays a non-steady inhibitory role at higher concentrations. IR spectra and XRD results revealed the presence of farringtonite at lower P2O5 additive concentrations and magnesium pyrophosphate at the higher concentrations, which lead to the increment of activation energies.