A continuous flow process for production of water-soluble Platinum-Dimercaptosuccinic acid (Pt(DMSA)) nanoparticles at ambient conditions using millifluidics is demonstrated. The process development was supported by in-situ synchrotron radiation-based X-ray absorption spectroscopy (XAS) investigations. The XAS revealed that the nucleation and growth of the Pt(DMSA) nanoparticles is extremely fast. Such a fast nucleation and growth process was also found to hinder coating of the channel walls, except at the zone 1 where the reactants first interact. The engineering of hitherto unreported Pt(DMSA) nanoparticles, well characterized using High-resolution transmission electron microscopy (HR-TEM), Scanning transmission electron microscopy (STEM), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infra-red spectroscopy (FT-IR), using continuous flow processes offers potential opportunities for scale-up. (C) 2015 Elsevier B.V. All rights reserved.