A series of tests were carried out, in the Design Department of the College of Aeronautics, on plain journal bearings, at higher pressures than are normally encountered in engineering practice. Pressures of 40,000 lb/in.2 were realised with a rubbing speed of 1.1 ft./min. Comparison between the various materials tested was effected by continuously rotating the bearings for fixed periods under various loads while friction and wear were measured periodically. The most outstanding combination was S.90 Chromium-plated running in a Hidurex Special bearing. Some other materials, listed in paragraph 8, were also found to be suitable although not so wear-resistant. All the materials tested suffered same surface damage which, in general, proved not to affect the bearing performance. An attempt is made to explain the behaviour of the bearings and thus indicate possible further materials which might prove suitable.