Abstract: The clean room heating jacket comprises an inner liner and an outer cover formed from flexible, static-dissipative, substantially particle-free fabric, an intermediate layer of resilient, substantially fiber-free insulative material and a flexible heating element disposed between the inner liner and the intermediate insulative layer. The inner liner, intermediate insulative layer and outer cover are configured to conform generally to the shape and size of the processing vessel for which the heating jacket is adapted. The jacket is of clamshell design wherein relatively opposing free edge portions are disposed in closely spaced relation to one another when the jacket is in a closed position and in generally planar, outwardly spaced relation to one another when the jacket is in an open position. A flap is attached to the outer cover in overlying relation to one of the free edge portions, and VELCROC.RTM.