Characterization of novel silicon pixel detectors based on the new HV-CMOS technology, for the ATLAS ITk upgrade and the future CLIC vertex detector. Both ATLAS ITk and the CLIC vertex detectors are designed with high demanding requirements, pushing to the limits the standard technologies used for silicon pixel detectors. The new HV-CMOS technology allows implementing a sensor and read-out device in the same silicon substrate, combining the high-voltage performance of planar silicon sensors with the signal amplification and digitization of dedicated read-out chips, eliminating the need of the detector hybridization. HV-CMOS monolithic prototypes have been investigated for implementation in the ATLAS ITk detector, while HV-CMOS devices implemented as capacitively coupled pixel detectors (CCPD) were investigated for the CLIC vertex detector. Monolithic and CCPD prototypes were simulated and tested with particle beams. Detection efficiencies above 99%, before and after irradiation, were measured, endorsing the technology to be used in future detectors.