Abstract: The invention is a jacketed polymer optical fiber which comprises: an optical fiber which comprises a core formed from a light transmitting polymeric material having a first refractive index and a cladding formed from a polymeric material having a second refractive index which is lower than the first refractive index; and a jacket about the optical fiber wherein the jacket comprises a chlorinated polyethylene. The jacketed fibers of this invention have a higher service temperature than polyethylene jacketed fibers. The jacketed polymer optical waveguides of this invention are jacketed under conditions such that the optical properties of the polymer optical waveguide are not substantially degraded. The jacketed polymer optical waveguides have relatively low brittleness at use temperatures, good rigidity, and good solvent resistance. They also contain no material which tend to migrate into the polymer optical waveguide.