The infrared multiphoton dissociation (IRMPD) of CDCl3 in the presence of O2 and NO2 as acceptor gases has been studied. We have worked with both pure CDCl3 and mixtures with CHCl3. The reaction mechanism following IRMPD of CDCl3 is discussed in detail. CCl2O, CCl4 and DCl were found to be the main products. With added O2, the observed CDCl3 dissociation was larger than with nonoxygenated acceptor gases. The reaction mechanism probably involves a catalytic cycle initiated by the oxidation of CCl3. With the aim of discriminating the different CDCl3 dissociation mechanisms, the IRMPD of CDCl3 in the presence of NO2 was first studied. In order to make evident the CDCl3 dissociation produced by the catalytic cycle, we then studied the IRMPD of CDCl3 in mixtures with CHCl3 with O2 as the acceptor gas. In this case, the dissociation mechanism subsequent to IRMPD is evidenced in the competence between the two isotopic species.