The Captain James Thomas House, which has Federal-style detailing, is on Killingworth Road, in the Ponsett District of Haddam. Capt. Thomas served in the Revolutionary War and returned to Haddam to farm on land given to him by his father, Lt. Ebenezer Thomas, in 1786. After occupying a house on Lynn Road, he moved to the one on Killingworth Road, which was completed by 1795. Rev. William C. Knowles, in his book By Gone Days in Ponsett-Haddam, Middlesex County, Connecticut: A Story (1914), writes of the house:
Large two-story house erected by Capt. James Thomas, soon after the Turnpike was opened. Was at one time a tavern. Capt. Thomas died in 1842. A few years later his son-in-law, Mr. Alfred Brainerd, came here to live. The present occupant is an enterprising Bohemian, Mr. Paul Jiroudek.