A hydrocarbon conversion process wherein a hydrocarbon feedstock is contacted with a magnetically stabilized fluid bed of particulate solids comprising a mixture of separate, discrete (a) magnetizable substantially non-catalytic particles, and (b) non-magnetizable catalytic particles. The particulate solids mixture is withdrawn from the magnetically stabilized, fluidized bed and separated into magnetizable, substantially non-catalytic particles and non-magnetizable catalyst particles. The non-magnetizable catalytic particles are thereafter regenerated and returned to the hydrocarbon conversion zone. The separated magnetizable, substantially non-catalytic particles are subjected to heat transfer prior to their return to the conversion zone.