Delayed coker is employed to convert vacuum residue to valuable distillate and petroleum coke as low value byproduct. The coke yield can be minimized by optimizing process parameters such as temperature, pressure, recycle ratio which are already optimized within the constraints, it’s difficult to reduce the coke yield by further optimization of these. In addition, feed properties like CCR, asphaltenes, metal and sulfur also contribute for higher coke make. Since the choice of better feed having lower CCR etc is not economical due to higher feed cost, hence there’s a need to develop suitable additives or any other means to improve the liquid yields within the constraints of existing operating conditions and feed quality in an economical way. As per coking reaction mechanism, the initial reactions in delayed coking are breaking of alkyl bonds in the substituents of the cyclic structures. Naphthenic rings are very rapidly dehydrogenate to form aromatic rings and the hydrogen released stabilizes the free radicals formed by the thermal cracking reactions. After the reactions proceed to a certain point, a second liquid phase, the mesophase forms. As the polycyclics dealkylate and dehydrogenate, they become even more aromatic. Eventually, these structures become insoluble in the more paraffinic bulk liquid phase. Condensation reactions predominate in the mesophase. There is little abstractable hydrogen so the main reaction path for stabilizing free radicals is the recombination of two free radicals. After the naphthenic rings become depleted, recombination of free radicals occurs which enhances coke formation. The proposed additive(s) should prevent or minimize these reactions so that distillate can be improved at the cost of coke make.