Abstract. Synthesis of different size of nano-and microparticles is important in designing nanostructured materials with various properties. Wet synthesis methods lack flexibility to create various sizes of particles (particle libraries) using fixed conditions without the repetition of the steps of the method with a new set of parameters. Here, we report a synthesis method based on nucleation and particle growth in the wake of a moving chemical front in a gel matrix. The process yields well-separated regions (bands) filled with nearly mono-disperse nano-and microparticles, with the size of particles varying from band to band in a predictable way. The origin of the effect is due to an interplay of a precipitation reaction of the reagents and their diffusion that are controlled in space and time by the moving chemical front. The method represents a new approach and a promising tool for fast and competitive synthesis of various sizes of colloidal particles.