The unwanted deposition of carbonaceous layers can compromise the efficient operation of processing equipment, particularly for the upgrading of heavy hydrocarbons. An experimental investigation was undertaken to study deposition from the vapor in a tubular test section downstream of a bench-scale continuous bitumen coking reactor. Results of the effects on deposition of coker reactor temperature, steam addition, vapor velocity, and heating or cooling of the produced vapor are presented. Evidence suggests that physical condensation of heavy hydrocarbon species rather than vapor-phase chemical reaction is the primary cause of deposit formation. Entrained droplets of partially converted bitumen also contribute to the deposit. Morphological and chemical characteristics of the deposits are described. Preliminary data are presented on the aging of the amorphous hydrocarbon deposit into coke.