The invention relates to a polymer of ethylene which has a .mu..sub.o/.mu..sub.2 ratio of at least 13; and a high load melt index HLMI lower than 8 g /10 min, and a value of tan .delta. at .omega./.omega.c=0.01 of less than 1.3, where .delta. is G''/G', .omega. is the frequency at which G'' and G' are measured and we is the frequency at which G''=G', and G and G'' are respectively the elastic modulus and viscous modulus, both measured in Pa at 190.degree. C.; a process for making the polymer using a catalyst comprising chromium supported on a silica-titania support is also described.