The subject of higher steam pressures and their application to the steam turbine has already been dealt with on several occasions during the last few years, and when the authors were asked to prepare a paper it was a question whether at the moment there were any additional facts which could usefully be brought before the engineering public.The purposes of this paper, therefore, are, in the first place, to set out in as simple a form as possible the theoretical and practical gains which may be expected from any increases in pressure over as wide a range as possible, at the same time taking into consideration other improvements which in recent years have been introduced into power station operation. Then an account—partly historical—is given of the work which has so far been done in the actual employment in steam turbines of pressures higher than those which we have come to regard as normal, and, in passing, reference is made to the design of high pressure boilers. Many examples of high-pressure steam turbines are described and classified and the effect of high pressures on the details of design is noted. Finally, the question of reliability of high-pressure installations in operation is discussed and comparison made with plants operating with more normal pressures.