This invention relates to silane moisture curable polymer composition and more particularly, to such a polymer composition that is highly diluted by a non-silane containing component, while retaining good high temperatures properties. The invention is a polymer composition comprising a base resin comprising less than 59 wt % of a silane crosslinkable polyethylene (A), an thermoplastic polyolefin free from silane groups (B) wherein the polymer composition comprise a filler with a BET Nitrogen Surface Area larger than 3 m2/g (C). The invention also relates to a cable layer of such polymer composition suitably a semiconducting layer of a power cable.