There is increasing interest in developing novel coatings to enhance the biocompatibility of medical implants. A key issue in biocompatibility research is platelet activation and aggregation on the biomaterials' surface. Stoichiometric and nonstoichiometric titanium nitride (TiN(x)) films were developed by sputtering as case study materials, for probing platelet activation behavior onto them. Atomic force microscopy (AFM) facilitates the real-time studies of cells and guarantees cellular viability. In this work a methodology for platelets study by AFM was developed. The morphological, structural, optical, and wettability properties of the TiN(x) films were obtained by AFM, x-ray diffraction, spectroscopic ellipsometry, and contact angle measurements.The properties of TiN(x) films were correlated with their thrombogenicity involving platelets' adhesion, activation and protein clustering mechanisms. It was found that the TiN(x) films stoichiometry and surface roughness affect the platelet response. The stoichiometric and smoother TiN films promote platelets adhesion and activation.