John Kilcoyne was born in Wolverhampton in 1880, the son of John and Mary Kilcoyne (nee Moran). He first joined the army in 1900 at the age of 18, and served in South Africa. He left the colours in about 1908 as a reservist. In 1911, he married Lydia Spencer, and they went on to have three children. He worked for the Wednesfield Weldless Steel Tube Company Ltd.
In August 1914 he was recalled, and served with the 2nd Battalion of the South Staffordshire Regiment (number 5921). He was killed on 13 December 1917, and is commemorated at the Etaples Military Cemetery in France. He is also named on the roll of honour of the Wednesfield company.