In this paper, we investigated the electrochemical metal-ion sensor activity of a manganese phthalocyanine (MnPc). For this purpose, interactions of MnPc with various transition metal ions were examined in solution and in solid state. MnPc forms aggregates only with Ag+ and Hg2+ ions selectively among various transition metal ions in solution, which indicates possible application of the complex as a metal sensor. For practical application, MnPc was immobilized in a polymeric cation exchange membrane, Nafion, on a glassy carbon electrode and used as an electrochemical receptor element. Sensor properties of MnPc were potentiometrically and amperometrically characterized as metal ion sensor with respect to reproducibility, repeatability, stability, linear concentration range, and sensitivity. (C) 2012 Elsevier B.V. All rights reserved.