Important Note: The reaction is mostly seen in the case of aldehydes and ketones having no α hydrogen and are put in strongly basic conditions. It is basically a disproportionation reaction i.e., the same molecule gets reduced and oxidised simultaneously. In case of Cross and Intramolecular Cannizzaro reaction, the bulkier group gets reduced while the other one gets oxidised. The hydrogen of the hydroxyl group comes from the base it's put into.