In 1774 he was encouraged by the government to conduct studies and make enquiries on plants and natural products of medical and economic value.
[2] In 1777 he was also appointed opium inspector at Patna and he sought to grow pan and produce toddy for arrack production.
Among the plant illustrations that Kerr sent to Cullen was that of burrum chundalli, a curiosity known for its rapid movements, which was later given the name Hedysarum by Hugo Arnot.
[9] With the assistance of his munshī, Kerr produced a manuscript translation from Persian which was titled A Short Historical Narrative of the Mahrattah State (1782) that is held at Glasgow.
Kerr was a friend of Patrick Russell who also joined the East India Company medical service.