The levels of intracellular K+ and thiols were measured synchronously in E. coli cells under starvation stress and osmotic upshock,alkaline shift and cytoplasm acidification. The level of nonprotein thiols increased in response to osmotic upshock and alkaline shift but decreased under cytoplasm acidification. A positive correlation between the changes in the K+ pool and the level of nonprotein thiols was found under osmotic shock and alkaline shift. Inverse correlation between these parameters was observed after the acidification of cytoplasm. It is supposed that there is a tight relationship between the levels of K+, nonprotein thiols and intracellular pH.