Oxidative recovery methods that use oxygen or air for recovery of homogeneous metal catalysts, such as cobalt catalysts, used in for example hydroformylation processes, can be hazardous. Explosive or flammable gas mixtures may be generated inside the process equipment, which can deflagrate upon any ignition source such as a static electricity discharge. The use of a flammable diluent has been found to be a very effective way of optimizing the recovery method, by bringing the resulting gas mixtures above their upper flammability limit. The offgas produced is then also easier to dispose of as a fuel, as compared to when a non-flammable diluent is used.