The aim of this study was to improve thermal stability, mechanical and surface properties of thermoplastic polyurethane (TPU) with the addition of colemanite. The TPU/colemanite composites having various ratios of TPU and colemanite were prepared. The chemical structure of the prepared composites was investigated by Fourier transform infrared spectroscopy (FTIR). Thermal properties of the samples were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Mechanical properties of the samples were characterized with stress-strain test. Hydrophobicity of the samples was determined by the contact angle measurements. Moreover, the surface morphology of the samples was investigated by a scanning electron microscopy-energy dispersive spectrometer mapping (SEM-EDS). Finally, the obtained results prove that the prepared composites have good thermal, mechanical and surface properties and that they can be used in many applications such as the electronic devices, materials engineering and other emergent.