The initiation of carbon nanofiber (CNF) growth on polycrystalline Ni foam was investigated by a combination of ex‐ and in‐situ methods, including scanning electron microscopy, X‐ray diffraction and Raman spectroscopy. Experiments were performed at low hydrocarbon partial pressure in order to slow down the initiation process. Very little to no CNFs were observed on reduced samples, which is caused by diffusion of C to the bulk of the Ni‐foam. This prevents formation of Ni3C as a precursor of Ni nanoparticles at low hydrocarbon partial pressure, acting as active particles for CNF formation. CNF growth was significant on oxidized samples and the initiation was slowed down by using extremely low ethylene pressure. Ni‐nanoparticles are capable of catalyzing CNF‐growth, provided these are isolated from the Ni bulk by unreduced NiO, resulting from incomplete reduction of the NiO layer.