A laboratory unit consisting of a reactor with loosely fitting rods was used to assess adhesion in coking petroleum resids. The relationship between adhesion and the temperature at which cracked tars are coked was determined. Adhesion as a function of temperature in coking straight-run resids with and without asphaltenes was assessed. The results established the necessity of lowering the rate of heat removal from the coked mass or reducing the intensity of reactor shell interaction with the coke. A criterion was obtained for predicting the intensity of coke interaction with the reactor surface based on the examination of coker feed as a disperse system.