Thomas made seven voyages from Bristol as a slave ship in the triangular trade in enslaved persons.

On her fourth such voyage,Thomas and five other enslaving ships, bombarded Calabar for more than three hours to force the local native traders to lower the prices they were charging for captives.

Thomas first appeared in Lloyd's Register (LR) in 1786, the volume for 1785 being unavailable online, if it even exists.

1st enslaving voyage (1785–1786): Captain William Vicars sailed from Bristol on 27 April 1785, bound for West Africa.

[4] Her owner, James Jones, testified to Parliament that on her first voyage Thomas had acquired 414–415 captives, and had buried some 10 or 12.

At St Vincent she discharged three crew members and enlisted three before sailing for Bristol.

[9] 4th enslaving voyage (1788–1789): Captain Thomas Phillips sailed from Bristol on 8 July 1788.

[10] Thomas arrived at Cape Coast Castle on 29 August and sailed two days later for Calabar.

She had reached St Vincent with 27 of her original crew, discharged three there, and enlisted one additional man before sailing for Bristol.

[12] Dolben's Act apparently resulted in some reduction in the numbers of slaves carried per vessel, and possibly in mortality.

[13] In 1788–1789, James Jones, Thomas's owner, had nine enslaving vessels at sea or on the coast of Africa.

She arrived at St Vincent and then Jamaica, with John Smith, master, on 25 May 1790, with 305 captives.

6th enslaving voyage (1791–1792): Captain Thomas Phillips sailed from Bristol on 26 February 1791.

[18] Thomas sailed from Africa on 7 September, and arrived at Kingston, Jamaica, on 9 November.

Sixteen men were discharged at Jamaica and seven new crew members, all French, were signed on.

[22] On this voyage Phillips, together with five other captains of slave ships, bombarded Calabar for more than three hours to force the local native traders to lower the prices they were charging for captives.

The bombardment by some 66 guns killed and wounded 50 or so of the local inhabitants and resulted in the traders agreeing to the prices the captains offered.