The invention relates to a polymer composition comprising a polyethylene, a crosslinking agent and antioxidant(s), wherein the polymer composition contains a total amount of vinyl groups which is B vinyl groups per 1000 carbon atoms, and B1≤B, wherein B1 is 0.12, when measured prior to crosslinking according to method ASTM D6248-98, the crosslinking agent is present in an amount which is Z wt %, based on the total amount (100 wt %) of the polymer composition, and Z1≤Z≤Z2, wherein Z1 is 0.005 and Z2 is 2.0, and the antioxidant(s) is/are nitrogen containing antioxidant(s) being present in an amount which is W wt %, based on the total amount (100 wt %) of the polymer composition, and W1≤W≤W2, wherein W1 is 0.005 and W2 is 1.0, an article being e.g. a cable, e.g. a power cable, and processes for producing a polymer composition and an article; useful in different end applications, such as wire and cable (W&C) applications.