Abstract: Method of and apparatus for temperature conditioning of matter of the type wherein matter to be conditioned is exposed to a vapor within a vessel for select heating and/or moisture absorption or desiccation. The system includes selectively providing a mixture of condensible and noncondensible gases while controlling the enthalpy, partial pressure and dew point thereof. The gas mixture is delivered to a vessel and interacted with matter disposed therein. The temperature of the matter is brought to the approximate dew point of the condensible and noncondensible gas mixture. In this manner, both the ultimate temperature and moisture content of the matter to be conditioned may be controlled by selectively controlling the aforesaid parameters of enthalpy, partial pressure and dew point. Control of the aforesaid parameters may likewise be affected by controlling the vessel pressure and the rate at which energy is supplied to the condensible and noncondensible gas mixture.