In 1959 Koh left for London and graduated from Hornsey College of Art and London University. While in London he was introduced to modernism, his distinct use of colour and form exemplified by works such as Fan Fern (circa 1969) currently on display at the National Gallery Singapore. He returned to Malaysia in 1963 and was involved in establishing the Fine Art department of the MARA School of Art & Design. He left Malaysia to pursue a Masters in Art Education at Indiana University, USA on a Fulbright scholarship and completed a Doctorate in Philosophy of Education before returning to Malaysia. He left for Australia in 1976 and took on a lecturing position in Adelaide for the next decade. While in Australia he exhibited regularly and worked extensively with celebrated Australian artist John Olsen. As a practising artist and art educator, he contributed to the development of many young artists across the region.
He has exhibited internationally at the X Biennial (Sao Paulo, 1969), ASEAN Mobile Exhibition (Kuala Lumpur, Singapore, Jakarta, Manila, Bangkok, 1974), Malaysian Art 65-78, Commonwealth Institute (London, 1978), and the Fifth Indian Triennale (New Dehli, 1981). An art theorist with a special interest in the theory of ‘colour’, Koh is also an active art educator but foremost a painter.