A series of Ni1-xCoxFe2O4 (x=0-1.0) ferrite nanoparticles were synthesized by a hydrothermal process and characterized for their microstructural, magnetic, and photocatalytic properties. The nanoparticles had uniform particle morphology with a nanoscale average particle sizes of similar to 14.8-29.4nm and a narrow band gap of similar to 1.75-1.91eV, which decreases with increasing Co content. The nanoparticles showed an excellent sunlight-excited photocatalytic activity to malachite green and naphthol green B in water. Moreover, obvious Fenton-like reaction was observed. The photodegradation and Fenton-like photodegradation rates increased as the Co content increased. Complete Co substitution for Ni cation resulted in an optimal effect. The photo-Fenton-like reaction in the degradation of the naphthol green B in a water is more obviously slower than that in the case of the degradation of the malachite green in water because the oxidation of H2O2 is unfavorable for the degradation of acidic naphthol green B. The measurement of oxidation-reduction potential of the nanoparticles in the photodegradation condition indicated a reductive characteristic enhanced with the increase of Co content. Furthermore, the nanoparticles possessed high saturation magnetizations of similar to 50.7-64.2emug(-1) and low coercivity similar to 0.4-1.7kOe, and so were well magnetic separable in finally degraded dye aqueous solution.