Human identification is a two-step process of initial identity assignment and later verification or recognition. The positive identification requirement is a major part of the classic security, legal, banking, and police task of granting or denying access to a facility, authority to take an action or, in police work, to identify or verify the identity of an individual. To meet this requirement, a three-part research and development (R&D) effort was undertaken Betac International Corporation, through its subsidiaries of Betac Corporation and Technology Recognition Systems, to develop an automated access control system using infrared (IR) facial images to verify the identity of an individual in real time. The system integrates IR facial imaging and a computer-based matching algorithm to perform the human recognition task rapidly, accurately, and nonintrusively, based on three basic principles: every human IR facial image (or thermogram) is unique to that individual; an IR camera can be used to capture human thermograms; and captured thermograms can be digitized, stored, and matched using a computer and mathematical algorithms. The first part of the development effort, an operator-assisted IR image matching proof-of-concept demonstration, was successfully completed in the spring of 1994. The second part of the R&D program, the design and evaluation of a prototype automated access control unit using the IR image matching technology, was completed in April 1995. This paper describes the final development effort to identify, assess, and evaluate the availability and suitability of robust image matching algorithms capable of supporting and enhancing the use of IR facial recognition technology. The most promising mature and available image matching algorithm was integrated into a demonstration access control unit (ACU) using a state-of-the-art IR imager and a performance evaluation was compared against that of a prototype automated ACU using a less robust algorithm and a dated IR imager. The further development of this demonstration ACU will lead to the production of a commercial IR facial imaging identity verification system capable of meeting a broad range of access control and other security and law enforcement applications.