To overcome the well-known problems encountered with surface fouling of carbon electrodes that occurred with many compounds, we report a simple and rapid method for the preparation of a disposable sensor depending on electrodeposition of porous Cu-microparticles on pencil graphite electrode (Cu-PGE) that can be applied for sensing antiviral compound valacyclovir (VAL). The bare and porous Cu-modified pencil graphite electrodes were characterized by cyclic voltammetry and SEM. The porous Cu-modified pencil graphite electrode displayed distinct electrocatalytic activities in response to the electrochemical redox reaction of Cu2+ ion in the Cu-VAL complex. Adsorptive square wave stripping voltammetry (AdSWV) was used for the direct electrochemical determination of VAL. Under experimental conditions, the modified electrode had a linear response range from 2.0x10-9 M to 1.0x10-8 M VAL with a detection limit of 1.78x10-10 M. The procedure was applied to the assay of VAL in tablets with mean percentage recoveries of 100.28%. The porous Cu-modified pencil graphite electrode (Cu-PGE) is fabricated utilizing a simple single method, and at an extremely low cost with high stability, sensitivity and offering a promising tool for sensing VAL in quality control laboratories and in stability studies.