C2H2, 40 mL/min, was cracked over (a) 9.3, (b) 11.0 and (c) 9.9% CO supported on gamma-Al2O3 (130), ZrO2 (29), and SiO2 (362 m(2)/g) carriers, resp., that had been wet-impregnated with Co(NO3)(2).6H(2)O, dehydrated in 24 h, dried 4 h/105degreesC, calcined in air 3 h/350degreesC, and reduced in situ with H-2 1 h/500degreesC, to deposit C whose output and reactivity were studied in relation to support type. The C-coated catalysts were heated 15degreesC/min in 50 mL/min of (I) (8:92 v/v) O-2-Ar and (II) (5:95 v/v) H-2-Ar to 800degreesC and 900degreesC, resp., and the effluent gas was mass-spectrometered in an Ametek's Dycor System 1000 quadrupole instrument. The C was deposited ascendingly, b < c < a, most and least extensively on a (2.1-3.0% and 46.1% over 200-250degreesC/1 h and 300degreesC/1 h) and c (0.24-0.29% and 2.0% at 200-250degreesC/1 h and 300degreesC/1 h), resp., and was most reactive on b. From the a, b, and c, the deposit was removed in experiments I as CO. most extensively over 265-360, 210-290, and 220-350degreesC, resp., and in experiments II mainly as CO and slightly (or nil from b) as CH4 over 450 to ca. 700, 400 up to 900degreesC. and at ca. 110degreesC and also 400 to ca. 440degreesC, resp.