In this article was studied pressure influence in the electrode block of the model of the lead-acid accumulator on the most important physical properties (a specific surface, pore size distribution, compression properties, speed of capillary lifting of electrolyte) of absorbent glass mat separators of the trademarks «Hollingsworth» (USA) and "Bernard Dumas"(France) and on efficiency of an oxygen cycle. It is shown that the highest compression properties separators with a high specific surface (7-10 m2 /g) possess.