This paper reports cyclic voltammagrame of several concentration ferrocene in 1-buty-3-methylmidazolium tetrafluoroborate(BMIMBF4)ionic liquid at various scan rates relative to Ag/Ag+ reference electrode with GC working electrode and Pt counter electrode.From the voltammetric data for ferrocene give diffusion coefficient of 7.2×10-8/cm2/s,which were fit to a reversible one-electron process.