One of drawbacks that aluminium alloy pressure vessels have suffered so far is attributed to the fact that the standards for the manufacture and the regulations in use are accordance with those for steel vessels. The only aluminium alloy which is approved for pressure vessels is 2017-T4, and their exploitation is restricted within carrying oxygen, nitrogen, carbon dioxide and air.This state of affairs caused incovenience on the part of the administration of industrial safety and, on the other hand, the demand for pressure vessels of corrosion-resistant aluminium alloy has been raised by the users.In March 1962, the competent authority suggested that a set of specifications should be drawn up for use of the other aluminium alloys for gas cylinders independent of customary circumstances and taking advantages of the characteristics of light metals, and consequently, the committee of Light Metals for Pressure Vessel was established in Light Metals Society. This report is a summary of studies that the committee has made carrying out various tests, such as, hydraulic stretch, alternate pressure, hydraulic breaking, repeating drop-impact and crushing tests, on the seamless cylinders of six kinds of materials having 7 litter capacity.The dimensions, the chemical compositions, the mechanical properties and the test procedures are shown in Table 1, 2, 3 and 4, respectively, and various test results are summarized in Table 12 compared with 2017-T4 cylinder.According to the above mentioned results, 5052-F, 5056-F, and 6151-T6 alloys are not inferior to 2017-T4 alloy as cylinder materials. The proposed specifications and the allowable stresses are shown in Table 14 and 15 respectively, and the standard of safty factor can be taken 3, approximately.