The effects of salt stress on photosynthesis, Mehler-peroxidase reaction (MPR) and the susceptibility of PS II to photoinhibition were investigated in Rurnex K-1 leaves. Salt stress resulted in dramatic decrease in photosynthesis, but had no significant effect on maximal photochemistry of PSII (Fv/Fm). During photosynthetic induction, a considerable electron flow was transported to oxygen in MPR both in control and salt-stressed leaves. Under steady state photosynthesis, enhanced electron flow to oxygen in MPR was observed only in salt-stressed leaves. The enhanced MPR in salt-stressed leave was accompanied by enhanced activities of scavenging enzymes, i. e. superoxidase dismutase (SOD) and ascorbate peroxidase (APX). In the presence of saturating CO2 decreasing oxygen concentration from 21% to 2% did not affect the susceptibility to photoinhibition in control leaves, but largely increased the susceptibility to photoinhibition in salt-stressed leaves. Based on these results, it is concluded that the enhanced MPR in salt-stressed Rurnex leaves serves as a sink to drain the excess electrons off the electron chain and thus mitigates photoinhibition.