The reaction involves the addition of  and cyanide () to the substrate.  Usually the substrate is an alkene and the product is a nitrile. 
The reaction proceeds via the oxidative addition of HCN to a low-valent metal complex to give a hydrido cyanide complex. Subsequent binding of the alkene gives the intermediate , which then undergoes migratory insertion to give an alkylmetal cyanide. The cycle is completed by the reductive elimination of the nitrile.
Lewis acids, such as triphenylboron (), induce reductive elimination of the nitrile product, increasing rates.
In the case of nickel-based systems, catalyst deactivation involves formation of dicyanonickel(II) species, which are unreactive toward alkenes.  The dicyanide arises via two pathways (L = phosphite):