In a process for recovery of values contained in solid carbonaceous material, the solid carbonaceous material is comminuted (10) and then subjected to pyrolysis, in the presence of a solid particulate source of heat in a pyrolysis zone, to form a pyrolysis product stream (24). The pyrolysis product stream contains a gaseous mixture and particulate solids. The solids are separated from the gaseous mixture to form a substantially solids-free gaseous stream (28) which comprises volatilized hydrocarbon free radicals newly formed by pyrolysis. The solid particulate source of heat is formed by oxidizing part of the separated particulate solids (32). Condensed stabilized hydrocarbons are obtained by quenching the gaseous mixture stream with a quench fluid (76) which contains a capping agent for stabilizing and terminating newly formed volatilized hydrocarbon free radicals. The capping agent is partially depleted of hydrogen by the stabilization and termination reaction. Hydrocarbons of four or more carbon atoms in the gaseous mixture stream are condensed. A liquid stream (64) containing the stabilized liquid product is then treated or separated into various fractions. A liquid containing the hydrogen depleted capping agent is hydrogenated to form a regenerated capping agent. At least a portion of the regenerated capping agent is recycled to the quench zone (34) as the quench fluid. In another embodiment capping agent is produced by the process, separated from the liquid product mixture, and recycled.