Abstract: A process for the pyrolysis of at least one material includes: introducing the material into a pressurized rotary retort system, heating the material in the pressurized rotary retort system within a desired temperature range and within a desired pressure range for a desired period of time; and, advancing the heated and pressurized material from a first end to a second end of the pressurized rotary retort by rotating the pressurized retort about its longitudinal axis; where at least a quantity of the material is converted into one or more end products. Also the system generally includes: a pressurized rotary retort system configured for producing at least one gaseous product from pyrolysis of material, and having a pressurized furnace vessel and a retort positioned within the pressurized furnace vessel; and; a solids reactor system operatively connected to the rotary retort for receiving material from the pressurized rotary retort system.