Moynan originally set out to study medicine, but opted for a career in the arts shortly before his final examinations.
By the late 1880s Moynan had returned to his native Dublin to exhibit his paintings, becoming a member of the Royal Hibernian Academy in 1890.
[1] In 1884, he married his cousin Suzanna Mary Moynan in her home on 9 April in Thurles, County Tipperary.
He was a leading exhibitor at the Royal Hibernian Academy with works such as "bleak house", "a travelling show" and "military manoeuvres" being some of the pieces displayed here.
In the final years of his life, there was little work created by him, only a final painting which was submitted to the academy in 1902 titled "The Death Of The Queen" which depicted the death of Queen Victoria and the reaction of people from Dublin who were standing around a newspaper boy.