James Hewetson, merchant and empresario, the son of Patrick and Honora (Hoyne) Hewetson, was born at Thomastown, Kilkenny County, Ireland, in 1797 or 1798. He studied medicine and came to the United States as a young man. He had decided to seek his fortune in Mexico when he met Stephen F. Austin at St. Louis, Missouri. He accompanied Austin to New Orleans and was one of Austin's party on his first visit to Texas in 1821. Hewetson left the Austin party at Bexar and went to Mexico, where he settled at Saltillo and Monclova. He engaged in mercantile, manufacturing, and mining enterprises and became influential in Coahuiltecan governmental circles. In 1826 he and James Power formed a partnership to establish a colony in Texas (see POWER AND HEWETSON COLONY). Hewetson became a Mexican citizen on August 11, 1827, but in later years seems to have considered himself a British subject. He fortified his position in Coahuila by marrying a wealthy widow, Josefa Guajardo, on April 29, 1833.
Although he had a headright in the Texas colony, Hewetson maintained his home in Coahuila and took no part in the Texas Revolution. After the war he visited Texas on several occasions and for a time lived at San Antonio, but he soon returned to Mexico. Accounts are replete with consistent generosities shown by Hewetson to Texans who passed through Saltillo as prisoners from the Texan Santa Fe and Mier expeditions and Adrián Woll's invasion. Hewetson died at Saltillo on September 12, 1870, and was buried there. His vast estates in Mexico and Texas were left to his wife's relatives.