The HKrCl complex with HCl is characterized by IR spectroscopy in a Kr matrix and by ab initio calculations. The HKrCl center dot center dot center dot HCl complex exhibits a strong blue shift of the H-Kr stretching mode in comparison with the HKrCl monomer, which indicates stabilization of the H-Kr bond upon complexation. The obtained maximal shift of ca. +300 cm(-1) is probably the largest blue shift experimentally observed for 1: 1 molecular complexes. The HCI absorptions are found to be strongly red-shifted upon complexation with HKrCl (up to ca. -500 cm(-1)). In the HKrCl synthesis procedure, an HCl/Kr matrix was first photolyzed at 193 nm to yield H and Cl atoms in a Kr matrix and then annealed at about 30 K to activate mobility of H atoms and to promote the H + Kr + Cl reaction. The HKrCl center dot center dot center dot HCl complex is mainly formed from the Cl center dot center dot center dot HCl intermediate complex that is produced by photolysis of HCl dimers. Bands of the HKrCl center dot center dot center dot(HCl)(2) complex are tentatively identified with a very large shift of ca. +700 cm(-1) for the H-Kr stretching mode, These experimental observations are supported and explained by ab initio calculations.