Abstract: A continuous process for the production of acetic acid by a catalytic gas-phase oxidation of butenes in the presence of a vanadate catalyst and steam and in a solid bed or fluidized bed reactor cycle is disclosed wherein the recycled gas stream contains acetic acid produced by the reaction of the butenes and oxygen or oxygen containing gases, and the butene proportion in the gaseous mixture is at least 0.4 percent by volume. A first portion of the gas stream leaving the reactor cycle is recycled and a second portion of the gas stream leaving the reactor is cooled whereby acetic acid and water are condensed. After branching the waste gas the remaining gaseous fraction of the second portion is recycled into the reactor. The volume ratio of this remaining gaseous fraction to the first portion is about 0 to 0.2 for an air feed and about 0.1 to 0.4 for an oxygen feed. The acetic acid has a concentration in the effluent gas of the reactor of about 1.5 to 10 percent by volume.