Abstract: A cross-linked polyolefin jacketing and/or insulating composition for use on wire and cable having superior resistance to the propagation of flame, a low smoke emission level and low emission of toxic byproducts when subjected to heat or flame, as well as low moisture absorption characteristics and high resistance to weathering, oils and chemicals, which comprises a polyethylene-vinyl acetate copolymer, magnesium silicate, and alumina hydrate in major proportions, and, in minor proportions, carbon black, polymerized 1,2-dihydro 2,2,4-trimethyl quinoline, stearic acid, vinyl-tris (.beta.-methoxethoxy)silane, triallyl cyanurate, and di-cumyl peroxide in anhydrous aluminum silicate.