The present invention relates to a process for the production of surface functionalised nanoparticles, such as the production of semiconductor quantum dot nanoparticles incorporating surface-bound functional groups which increase the ease with which the dots can be employed in applications, such as incorporation into solvents, inks, polymers, glasses, metals, electronic materials and devices, bio-molecules and cells. The method comprises reacting first and second nanoparticle precursor species in the presence of a nanoparticle surface binding ligand X-Y-Z wherein X is a nanoparticle surface binding group, Y is a linker group, and Z is a functional group, in which Y comprises a polyethyleneglycol group and/or Z comprises an aliphatic group incorporating a terminal unsaturated group, said reaction being effected under conditions permitting binding of said surface binding ligand to the growing nanoparticles to produce said surface functionalised nanoparticles.