Thin films of metals are important for several technological applications such as catalysis and electrical contacts. One of the most important methods for depositing metals is chemical vapor deposition (CVD) where a film is deposited on a surface by surface-, and sometimes also gas phase-, chemical reactions between precursor molecules. A fundamental chemical reaction in most CVD processes for metals is a reduction where the positive valence, i.e., ionic state, of the metal center in the precursor molecule is reduced to a zero-valent, metallic state. The reduction is done by a molecular reducing agent, providing electrons, by undergoing oxidation. For very electropositive metals, the reduction is not favored thermodynamically, and powerful reducing agents and/or high temperatures are therefore needed to deposit a metallic film of e.g., many of the first-row transition metals. We have recently presented an alternative CVD approach to thin metallic films where the free electrons in a plasma discharge are used for the reduction at the surface of the growing film. This is done by applying a positive bias to the substrate holder to attract the plasma electrons to the substrate surface. We have demonstrated that the new CVD method uses the plasma electrons for the deposition by showing that films are only deposited when a positive bias, attracting electrons, is used on the substrate holder, while no films are deposited when a negative bias, repelling electrons, is used. Also, the CVD method only functions on low-resistivity substrates, where the electron current from the plasma can be conducted away. Although these results strongly suggest that the plasma electrons are active in the surface chemistry, more advanced in-situ measurements are needed to form a surface chemical model of the deposition chemistry in the new CVD method.