Abstract: A multi-zone fluidized bed hydrocarbon conversion process and apparatus for producing gas and distillable liquid products from heavy hydrocarbon feedstocks. The feedstock is introduced into an upper fluidized bed primary cracking zone maintained at temperature of 850.degree.-1400.degree. F. for cracking reactions therein, and resulting tars and coke are deposited on and within a particulate carrier material contained therein. The carrier material containing said tars and coke descends successively through a stripping zone to remove tars and an interim controlled temperature zone for secondary cracking against an upflowing hot reducing gas, then descends into a lower fluidized bed gasification zone. The gasification zone is maintained at temperature of 1600.degree.-1900.degree. F. by oxygen-containing gas and steam introduced therein to gasify the coke deposits and produce the reducing gas.