The main objective of this study is to investigate the structural features, magnetic behaviour, photocatalytic properties and blood compatibility of NiFe2O4 nanoparticles (NPs) obtained by subnanosecond laser ablation in water. Structure and size distribution of NPs were studied using X-Ray Diffractometry (XRD) and Transmission Electron Microscopy (TEM). The photocatalytic properties of NPs were evaluated by photo-degradation of Methylene Blue (MeB) dye under ambient visible light illumination. Four different kinetic models were used to identify the photocatalytic degradation mechanism of NiFe2O4 nanoparticles and it was found that the pseudo-second-order model was the most suitable type to interpret the experimental kinetic data of MeB photodegradation. The hemocompatibility of NiFe2O4 nanoparticles was studied by hemolysis tests using human erythrocytes drawn from healthy volunteers. NiFe2O4 nanoparticles caused undesirable hemolysis ratios at 0.05, 1 and 5 mg/ml concentrations, while the biologically safe concentration of these nanoparticles was found to be below 0.01 mg/ml. (C) 2020 Elsevier B.V. All rights reserved.