A process for producing product particles includes producing, by means of a droplet-based microfluidic technique, a plurality of primary droplets of a first liquid phase dispersed in a continuous second liquid phase. The first liquid phase is immiscible with the second liquid phase. An emulsion of the primary droplets in the second liquid phase is formed. A liquid adjunct is admixed with the emulsion. The liquid adjunct comprises secondary droplets of a third liquid phase, and/or particles, dispersed in a fourth liquid phase. The third liquid phase and/or the particles and/or the fourth liquid phase include a reagent capable of reacting with a component of the first liquid phase. The secondary droplets and/or the particles (whichever is/are present) are smaller than the primary droplets. The secondary droplets are allowed to coalesce with the primary droplets, and/or the particles are allowed to mix with primary droplets, thereby to form tertiary droplets. In the tertiary droplets, the reagent is allowed to react with the component of the first liquid phase, so that product particles are formed from the tertiary droplets. The product particles are recovered from the second liquid phase.