Composite filter media which are highly resistant to thermal degradation and retain filter efficiency and extended lifetime in high temperature environments are disclosed. Methods of making the filter media are also disclosed. A composite filter media for removal of particles from a gas stream includes a layer of a porous polymeric membrane, the layer having an upstream side and a downstream side relative to the direction of the gas stream; and at least one layer of an electrostatic microfiber web containing an antioxidant in an amount ranging from about 0.1% to about 10% by weight; the at least one layer of microfiber web disposed on the upstream side of the porous polymeric membrane layer.