The provider of specialty chemicals for the oil and gas industry said the deal will speed the expansion of its operations in the west Texas Permian Basin and the Eagle Ford shale region in south Texas.
Financial terms of the deal were not immediately available, but the company said it would pay a combination of cash and shares escrowed over a three-year period.
CES also said that key employees have agreed to employment contracts along with non-compete and non-solicit commitments.
"We are acquiring an established west Texas based production and specialty chemicals company, with experienced management, great customers, and excellent production and specialty chemicals sales, technical and field personnel," CES president and chief executive Tom Simons said in a statement.
Southwest will become part of CES's JACAM division under the brand JACAM Southwest.
"The combination of our team, our customer relationships in Texas and our expertise, together with JACAM's unique product offerings and manufacturing capabilities will be a powerful partnership for growth," said Southwest founder Paul Stephens.
CES share closed down 14 cents at $10.56 in trading on the Toronto Stock Exchange on Thursday.