Norits RB2, RB4; Sorbonorits 3, 4; and Polish Gryfskand AHD, NG I, and NG II activated C were heated inductively (0.803-1.011 kg C, 6 A, 80-90 V, 50 Hz, 4 steel cores; 0.873-1.376 kg C, 20 A, 75-85 V, 50 Hz, no steel cores), each packed as an identical-volume bed in an 80x475 mm polypropylene column (carrying 750 Cu wire coils) with or without 4 concentric (half-radius away from column wall) ferromagnetic steel cores, 10(phi) x450 mm in size and 1.131 kg in total wt., and the time to attain 100degreesC in the bed was measured. The Dutch and the Polish C had sp. surfaces 960-1400 and 700-900 m(2)/g; particle diameters 2-4 and 1.4-3.5 mm; bulk d. 380-520 and 420-550 kg/m(3); and sp. resistances 0.088-0.12 and 0.175-0.3 Omega.m at 25degreesC; 0.058-0.088 and 0.117-0.197 Omega.m at 100degreesC, resp. The heating power efficiencies measured with (without) the cores placed In the bed were 18.7(10.9) (AHD)-53 (14)% (RB2), resp., and the times to attain 100degreesC were, e.g., 390(1580) (Sorbonorit3), 490(960) (RB2), 1360(2080) (AHD) s, resp. Radial temperature gradients were the only drawback to the cores.