The invention relates to a process for producing phosgene by conversion of chlorine and CO over an activated carbon catalyst, wherein the activated carbon catalyst is dried by reducing the water content, where the drying comprises the following steps:



a) contacting the catalyst with an inert gas stream
b) determining the residual moisture content of the catalyst by determining the moisture content in the offgas stream
c) ending the drying process after attainment of the desired moisture content in the offgas stream by switching from the inert gas to the reaction gases and optionally
d) heating up the catalyst bed and/or the inert gas during the drying process.