The infrared spectrum of CO 2 -Kr complex is studied in the region of the carbon dioxide ν 3 fundamental vibration ( � 2350 cm À 1 ). Tunable IR radiation from an OPO is employed to record absorption spectrum of the complex generated in a pulsed supersonic slit jet. The spectrum exhibits broadening and splitting of transitions due to mass dependence of the five Kr isotopes with natural abundances exceeding 2 %. Good simulation of the spectrum is achieved by scaling the vibrational and rotational parameters. This scaling model is partic-ularly important for the combination band involving the intermolecular bending mode where many isotope splittings are observed. As with other CO 2 -rare gas complexes, we also observe weak hot bands of CO 2 -Kr transitions corresponding to the hot band originating in the CO 2 intramolecular bend. From these we determine a splitting of 1.418 cm À 1 between the inplane and out-of-plane bend of CO 2 , due to the neighboring Kr atom.