A new thiomorpholine-functionalized nanoporous mesopore Mobil Composition of Matter No. 41 (MCM-41), abbreviated as TMMCM-41, was synthesized and applied as a sensing material in construction of a cadmium carbon paste electrode. The electrode composition of 20.1%wt TMMCM-41, 54.0% graphite powder, 25.9% paraffin oil showed the stable potential response to Cd2+ ions with the Nernstian slope of 28.6 mV decade−1 (±1.8 mV decade−1) over a wide linear concentration range of 10−6 to 10−2mol L−1 with a detection limit of 6×10−7 molL−1. The electrode has fast response time and long-term stability (more than 4 months). The proposed electrode was used to determine the concentration of cadmium in tap water contaminated by this metal and cadmium electroplating waste water samples.