The halophytic species Mesembryanthemum crystallinum was induced to exhibit CAM-like CO2 gas-exchange reactions with a depression of net CO2 uptake during the day and a net CO2 uptake during the night by treatment with 400 mM NaCl. The induction of CAM is favored by relatively high day temperatures and relatively low night temperatures. Net CO2 uptake in the dark is largely increased by an interruption of water absorption by the plants, whereas light CO2 fixation is decreased by this treatment. When plants are rewatered after a two days drought period, net CO2 uptake in the dark is clearly favored over CO2 light fixation. During the post-stress period a slight reduction of leaf chlorophyll content becomes apparent. Under the experimental conditions used a reversibility of CO2 fixation metabolism from CAM to C3 is observed when salt-treated plants are transferred to non-saline root medium. This is paralleled by a largely enhanced leaf expansion and a drastically increased leaf water content.