Abstarct: Recently, magnetic nanoparticles have extensively been employed as alternative catalyst supports, in view of their high surface area resulting in high catalyst loading capacity, high dispersion, low toxicity, environmental protection, outstanding stability, and convenient catalyst recycling. In the present study, magnetite nanoparticles, NiFe2O4@Ag and NiFe2O4@Mo, were synthesized and characterized and their antimicrobial activities and also the catalytic properties were tested, afterwards. For the synthesis of NiFe2O4@Ag nanoparticles, silver ions were loaded onto the surface of the modified NiFe2O4 and reduced to silver nanoparticles by adding NaBH4. Antibacterial effects of NiFe2O4@Ag were examined against two species of soil and plant related bacteria named Bacillus subtilis (gram positive) and pseudomonas syringea (gram negative), respectively. Antifungal activity of nanoparticles were evaluated against two species of plant pathogenic fungi called Alternaria solani and Fusarium oxysporum. Biological results indicated that the synthesized materials have shown an excellent antibacterial and antifungal activity against both of bacteria and fungi, which their growth were completely inhibited after 24 h contact with NiFe2O4@Ag. For the synthesis of a heterogeneous catalyst NiFe2O4@Mo, complex Mo(CO)6 was loaded onto the surface of the modified NiFe2O4 nanoparticles. This catalyst was found as an efficient catalyst for epoxidation of cis-cyclooctene and a wide variety of alkenes, including aromatic and aliphatic terminal ones using tert-butyl hydroperoxide as oxidant. This new heterogenized catalyst could easily be recovered by using a magnetic separator and reused four consecutive and only 13% of its catalytic activity fell.