A perfluoropolyether and a composition comprising the perfluoropolyether are provided in which the perfluoropolyether comprises at least one bromine or iodine atom at the primary position of the perfluoropolyether. Also provided is a process for producing the composition in which the process comprises contacting a perfluoropolyether acid fluoride moiety with a metal bromide or metal iodide or a suitable polyether secondary iodide under a condition sufficient to effect the production of a perfluoropolyether comprising at least one bromine or iodine at the primary position.