Disclosed herein is a process for the preparation of a stable sustained-release biocidal composition containing microencapsulated biocide and wherein the process comprises the steps of: (i) adsorbing the biocide onto an inert carrier by grinding to attain the required particle size and wherein the ratio of biocide inert carrier is in the range of about 1:99 to about 99:1 (ii) optionally coating with an appropriate amine or imine compound or a water resistant film forming polymer and dispersing the resultant biocide encapsulated inert carrier in an aqueous medium in the presence of suitable dispersing agent (iii) adding at least one thickening agent to re-disperse the encapsulated biocide containing partial amount of non-encapsulated biocide if any and (iv) preparing an aqueous or solvent based sustained release biocide dispersion. Also disclosed is a stable, sustained-release biocidal composition prepared by such process and uses thereof.