Ferroelectric nanoparticles, due to their high non-linear optical response, are of considerable practical interest for their use as nanoprobes for the study of biological materials by multiphoton microscopy methods. To prevent toxic effects, it is necessary to modify the surface using biocompatible polymers. Here we report the results of the study on the effect of surface modification of BaTiO3 nanoparticles with hydrolyzed chitosan obtained from shrimp exoskeletons (Penaeus vannamei). It was found that increasing of the hydrolyzed chitosan concentration in the solution during surface modification from 1 to 3% leads to a significant reduction in nanoparticle agglomeration, while the intensity of the second harmonic generation changes insignificantly. Graphical abstract: [Figure not available: see fulltext.].