Abstract: Photoionization and photodissociation of diethylzinc (ZnC4H10) were performed using vacuum ultraviolet (VUV) synchrotron radiation and a time-of-flight mass spectrometer (TOF-MS). The photoionization mass spectra of all the observed ions fromdiethylzinc and their photoionization efficiency (PIE) curves with the photon energy from8 to 22 eV were measured. From their PIE curves, the ionization potential (IP) of ZnC4H10 (IP=8.20±0.05 eV) and appearance potentials of fragment ions (ZnC2H5+, ZnH+, Zn+, C2H5+, C2H3+, etc.) were obtained. According to the gas phase energetic data from references, the formation enthalpies of chief ions were evaluated and their possible channels of dissociative photoionization as well as their branch rates were discussed. The results indicated that the chief channels were the simple cleavage of Zn—C bond in the parent ions to form fragmental ions C2H5+ and ZnC2H5+ which further dissociated to Zn+ ion. More than 75%of the total production ions belonged to Zn-containing ions.