The invention relates to a process for increasing the carbon monoxide content of a feed gas mixture comprising carbon dioxide, hydrogen and carbon monoxide via a catalytic reversed water gas shift reaction, comprising the steps of (1) heating the feed gas mixture having an initial feed temperature of at most 350° C. in a first zone to a temperature within a reaction temperature range in the presence of a first catalyst; and (2) contacting the heated feed gas in a second zone within the reaction temperature range with a second catalyst. This process shows relatively high conversion of carbon dioxide, and virtually no methane or coke is being formed, allowing stable operation.