A thermally insulated apparatus provides a substantially adiabatic environment for elevated temperature liquid chromatography applications. The thermally insulated apparatus minimizes or eliminates temperature gradients between columns and mobile phases, and maintains a temperature at or near the set point of an operably coupled heating means. The apparatus is also effective when used in conjunction with a liquid mobile phase heater such as those provided by an HPLC column compartment or a metal capillary of sufficient length to heat the liquid mobile phase.