A thermoplastic olefin (TPO) composition comprises (1) a major amount by weight of (a) a substantially linear homopolymer or copolymer of a C.sub.2 C.sub.10 .alpha.-olefin in major proportion to (b) a long chain branched a linear homopolymer or copolymer of a C.sub.2 C.sub.10 .alpha.-olefin, (2) a minor amount by weight of a cross linkable elastomer, and (3) at least one thermally decomposing free radical generating agent present in an amount sufficient to promote an increase in melt strength of the composition over that of the melt strength of the linear homopolymer or copolymer of a C.sub.2 C.sub.10 .alpha.-olefin alone and insufficient to substantially degrade the .alpha.-olefinic polymers. The TPO composition is prepared by melt blending the components at a temperature sufficient to melt said homopolymers or copolymers of a C.sub.2 C.sub.10 .alpha.-olefin and thermally decompose said agent. Articles are thermoformed from the thermoplastic olefin.