Nanoparticles, especially gold nanoparticles (AuNPs), received extensive attention in many industrial and research fields including pharmaceutical, catalytic, electronic, health care, imaging, sensing and cosmetic production. AuNPs show interesting chemical, physical and magnetic properties which depends on their size, size distribution, surface and morphology. Precise control of size and surface properties of nanoparticles is a challenge in batch synthesis processes due to poor mixing, poor control of heat and mass transfer and batch-to-batch variation. In contrast, continuous synthesis of nanoparticles in microscale channels provides precise control of fluid dynamics which allows enhanced tuning of the of nanoparticle end-use properties. This thesis investigates effective and robust ways to synthesise bespoke AuNPs using glass capillary microfluidics at room temperature.