The present subject matter describes a method and apparatus for operating a delayed coker. The method comprises contacting a vapour produced in a delayed coker-drum with a catalyst maintained in form of a bed, and maintaining a level of said catalyst-bed within pre-defined limits during catalytic-cracking of the vapour. Thereafter, the cracked-vapour is routed to a coker-fractionator column to trigger conversion into one or more hydrocarbon products.