The invention provides a solvent-free biocidal composition of improved efficacy comprising at least one water insoluble biocide (preferably a herbicide) and a water-soluble carrier material, wherein the water-insoluble biocide is dispersed through the carrier material in nano-disperse form having a peak diameter of the nano-disperse form below 1000nm. The invention also provides a process which comprises spray drying a solution of the biocide and a solution of a water-soluble carrier to obtain a solvent free dispersion of the biocide in the carrier, which, when dissolved in water, produces a nano-disperse biocide. The invention also provides an aqueous dispersion of a water insoluble biocide and a water-soluble carrier obtained by the dispersion of the composition of the solvent free composition in water.
