This paper reports an experimental study of coke deposit on Cr2O3/Al2O3 beds during the butene-l dehydrogenation reaction under different reaction conditions. The coke profiles in the beds were strongly affected by temperature, butene concentration and reaction times. The hydrogen content in the coke presents a profile inverse to that of the coke along the reactor. Coke concentration proved to be the variable which really influenced coke composition, independent of reaction conditions. The equation relating both variables is n = 0.3469 + 2.541 exp(-C-c/S-e/0.0187) where n is the H/C relation, C-c the coke concentration in percentage, and S-e the specific surface area.