The effect of solvent on the reductive electrografting of acrylonitrile (AN) onto nickel cathodes has been studied in dimethylformamide (DMF), a solvent for polyacrylonitrile (PAN), and in non-solvents that include acetonitrile (ACN), propylene carbonate (PC) and pyridine (PY). Electrografting responsible for the cathode inhibition has been observed for the first time in PC and PY. Not only the polymer-solvent interactions but also the intrinsic polarity of the solvent have an effect on the intensity of the inhibition peak which is the signature of the electrografting reaction. Concentration of the monomer in the electrode double layer appears to decrease as the solvent polarity is increased, consistently with a more efficient displacement of the monomer by a more polar compound. That such a competition occurs is also supported by the effect of the nature and concentration of the conducting salt. The best quality films are formed in DMF, which is a solvent for PAN. Quartz microbalance experiments have emphasized the crucial importance of the potential range used for the AN electroreduction, particularly in a solvent of the polymer.