The new Co(II)-carboxamide complex (1) and Co 3 O 4 nanoparticles (2), by way of thermal decomposition of (1) have been efficiently synthesised in the environment-friendly. X-ray diffraction reveals a slightly distorted octahedral coordination of cobalt (four nitrogens and two oxygens) in (1) and regular octahedral or tetrahedral ones (oxygens only) in (2). The investigation of (1) and (2) in the Mizoroki-Heck and epoxidation of alkens reactions showed them both to be powerful, green and inexpensive catalysts. K E Y W O R D S co (II)-carboxamide complex, Co 3 O 4 nanoparticles, epoxidation, Mizoroki-Heck, X-ray crystal structure