Sensing intracellular level of hydrogen peroxide (H2O2) is an extremely important task, because the overproduction of H2O2 causes cell mutations and the development of various pathologies. Eu3+-doped GdVO4 NPs has a great potential as multifunctional theranostic agent, as well as a sensor of intracellular H2O2. Therefore, detailed studies of all factors affecting their catalytic and luminescence properties, including the impact of H2O2 on their luminescent properties, are required. In present study, we have analyzed the effects of H2O2 on Eu3+ luminescence intensity in GdVO4:Eu3+ NPs synthesized in a water solution. As-synthesized NPs were characterized by XRD, HR-TEM, XPS and optical spectroscopy techniques. To analyze the surface modification of GdVO4:Eu3+ NPs after H2O2 exposure, XPS analysis and time-resolved luminescence spectroscopy were also used. Two mechanisms responsible for the observed Eu3+ luminescence quenching in GdVO4:Eu3+ NPs were found: (i) the decrease in the efficiency of non-radiative resonance energy transfer through the vanadate VO4 3- groups to Eu3+ ions due to the scattering effect of V4+ ions and (ii) the direct quenching of Eu3+ luminescence by –OH groups formed at the surface of NPs as a result of H2O2 decomposition.