With Co/GC ion implantation modified electrode as the working electrode, in 0. 1mol/L HAc-NaAc (pH= 4.96) buffer solution, a sensitive reductive wave of methotrexate was obtained by linear sweepvoltammetry. The peak potential was -0. 95 V(vs. SCE). The peak current was proportional to the con-centration of methotrexate in the range of 2. 2 × 10-7~8. 8 × 10-6 mol/L with the detection limit of 1.1×10-8 mol/L. The behavior of the reduction wave was studied and applied to the determination ofmethotrexate in tab...