Kim was born in Preston, Lancashire where he went to Hutton Grammar School. He studied medicine at Selwyn College Cambridge, University College Hospital, London and Stanford University, California. After working as a junior doctor in a number of London teaching hospitals he became a senior registrar at the Royal Brompton Hospital where he was also a lecturer at the National Heart & Lung Institute.
Kim moved to Swansea in 1994 to work as the Consultant Chest Physician at Morriston Hospital where he set up the Respiratory Unit. Throughout his time in Swansea, Kim has pursued his research interests, which include pulmonary fibrosis and cough. He has written over 60 papers in medical and scientific journals and a number of chapters in books including the Oxford Textbook of Medicine. He was co-author of the NICE Guideline on diagnosis of Idiopathic Pulmonary Fibrosis (2013) and Chairman of the British Association for Lung Research (2005 – 2010). Kim is now semi-retired and continues his research interests in pulmonary fibrosis.