Mr Reginald Clair Mattiske was born on 22 June 1912 in the regional town of York, Western Australia. He received his education at York State School, Northam High School, Perth Modern School, and the University of Western Australia.
In 1928, he began his career as a junior clerk in the state Premier's Department and eventually became an accountant for the State Gardens Board and the Perth Zoo.
On 17 August 1937, he married Ms Kathleen Eva Gratwick, and they had one daughter.
Promoted to inspecting accountant in the Treasury Department on 19 March 1940, Mr Mattiske enlisted for service in World War II with the Perth-based 5th Anti-Aircraft Battery on 30 January 1942.
In 1945, Mr Mattiske played a key role in establishing the Building Industry Congress of Western Australia and became its organising director. He then worked as a public accountant in private practice from 1946 to 1974. He served as a member of the Perth Road Board from 1953 to 1957 and was appointed a justice of the peace in 1954.
After leaving politics, Mr Mattiske continued his accountancy practice. He was state president of the RSPCA from 1961 to 1979, a director of the Perth Building Society from 1966 until 1983, and the honorary consul of Finland in Perth from 1972.
Mr Reginald Clair Mattiske passed away in 1992 in Perth, Western Australia.