The present invention provides the compounds of general formula 5 and 9 useful as potential antitumour agents against human cancer cell lines. The present invention further provides the process for preparation of napthalimide-benzimidazole hybrids of general formula 5 and 9, n-1-2, R=n-methylpiperazine or morpholine (Formula 9), wherein: n=2-3, m=2-3 and R=n-methylpiperazine or morpholine.