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This dissertation was written as a part of the MSc in Environmental Management and Sustainability at the International Hellenic University and investigates the precipitation of calcium carbonate nanoparticles using a hollow fibre gas liquid membrane contactor / precipi-tator concept. The current climate challenges and subsequent need for this technology are reviewed, with emphasis on the cement industry. A summary of CCUS, mineralization, and membrane technologies is presented, as well as a review of current applications in the literature. Experiments were conducted using a custom precipitator operating in bubbling mode with titania (TiO2), zirconia (ZrO2), and alumina (Al2O3) single tube ceramic membranes. Mem-branes were treated with hexyltrimethoxysilane to increase hydrophobicity, using either im-mersion (TiO2, ZrO2) or chemical vapour deposition (Al2O3). Polypropylene polymeric mem-branes were also used in two different 3MTM Liqui-CelTM hollow fibre membrane modules, operating in contactor and bubbling modes. The liquid phase was a solution of calcium chlo-ride (CaCl2¬), ammonium hydroxide (NH4OH3) and double distilled water and the gas phase was pure CO2. Samples were taken in five-minute intervals to measure pH and temperature, and experiments were terminated when a plateau of pH variation was observed. All liquid was vacuum filtered, and the precipitate was dried overnight at 110⁰C then weighed. Scanning electron microscopy (SEM) and X-Ray Diffraction (XRD) were used to characterize the crystal size and morphology. Comparisons were made between three groups to assess the effect of changing process parameters, including differences between ceramic membrane materials, dif-ferences between ceramic and polymeric membranes and finally the effect of only varying liq-uid flow rate in polymeric membranes. Reactions progressed similarly for all experiments with a rapid decrease in the first fifteen minutes before slowing. The production rate for ceramic membranes ranged from ~1-4g/h whereas polymeric membranes were all less than 1 g/h. SEM images reveal rhombohedral cal-cite with crystal sized between 1-4μm for ceramic membranes and less than 3μm for polymer-ic membranes. Nanoparticles were detected. XRD confirms the presence of pure calcite and no variation between the calcite main peaks was present. The average crystallite size was similar for all experiments (~52-53nm).