A study of the pyrolysis of a series of neopentyl-type xanthate esters was carried out at 250 °C. The formation of olefins and dithiolcarbonates were found to be two competing processes. The olefin formation process became more important when the number of β-phenyl groups increased and when there was an electron donating group substituted at the para-position of the β-phenyl ring. Kinetics studies supported the proposal that the transition state of the olefin formation process involved a stabilized phenonium ion. However the dithiolcarbonate formation became more important when there was the least number of β-phenyl substituents and this rearrangement appeared to proceed through a concerted four-membered cyclic transition state.