We report a highly selective and sensitive electrochemical method for the detection of mobile zinc ions (Zn2+) useful for early diagnosis of prostate cancer. The working electrode on a screen-printed electrode (SPE) was modified with zincon and electrochemically exfoliated graphite complex (zincon-EG) to afford the binding of Zn2+ on zincon-EG/SPE. UV-vis and FT-IR were used to characterize zincon-EG, XRD and SEM for zincon-EG and zincon-EG-enriched with Zn2+, and cyclic voltammogram for binding of Zn2+ at zincon-EG/SPE. The optimal conditions for detecting Zn2+ were with Tris-HCl as an electrolyte (pH 7.5) over 5 min of pre-concentration and applying electrodeposition potential of -1.2 V for 100 s. Differential pulse voltammetry (DPV) was used to establish the calibration curve and the linear range of Zn2+ detection in buffer solutions as 0.25 to 1.5 mg/L. The prepared zincon-EG/SPE sensors show good repeatability (RSD = 6.9%, n = 5) and are stable for over two weeks. Three mouse serum samples derived from transgenic adenocarcinoma of mouse prostate (TRAMP) were used as real matrices for testing by after diluting (500 x) and spiking with different amounts of Zn2+ (0.5, 1.0, 2.0, 3.0, 4.0 mg/L) through standard addition. From the DPV data, the original concentrations of mobile Zn2+ in the three serum samples were determined as 50, 41.5 and 5 mg/L. The average Zn2+ detection sensitivity, based on the linear responses obtained with our sensor, is 2.5 mg/L and the limit of detection is 5 mu g/L.