Thomas Andrews, son of a local linen merchant, was educated at Belfast Academy and at the Royal Belfast Academical Institution. On leaving school, he spent some time in his father’s business before entering Glasgow University in 1828, where he studied chemistry. After 1830, he took up the study of medicine, firstly at Trinity College, Dublin and thereafter at Edinburgh. In 1835 he obtained the degree of MD from the latter university and also received the diploma of the Royal College of Surgeons. He settled in Belfast, where he maintained a medical practice and taught chemistry at the Academical Institution. He pursued both occupations until 1845, when he was appointed vice-president of Queen’s College. Besides holding the position of vice-president, he was appointed Professor of Chemistry at the college in 1849.