(A) Air-borne H2O or (B) liq. H2O was sorbed on 4 microporous C (S-BET, 877, 1351, 1873, and 2164 m(2)/g; pore vol., 0.445, 0.749, 1.037, and 1.044 cm(3)/g;particle size 0.5-0.71 mm; (A) H2O sorbed, 10.25, 6.45, 8.55, and 4%.), and the specimens were kept 2 h at 77.4 K, heated to 20degreesC, dehydrated, and reheated at 473 K/1 mubar. The S-BET, and pore vol. rose by (A) 4.4-7.2 and 5.2-8.4; (B) 6.1-10.5 and 7.1-0.4%, resp. Freezing affected the proportions of micro and meso pores, the C becoming more heterogeneous. As the micropore share rose, the C became more fractal. On the A-modified carbon, tert-Bu benzene was adsorbed more effectively.