The construction and performance characteristics of PVC membrane (PME) and coated graphite (CGE) Fe3+ ion selective electrodes based on 1-phenyl-3-pyridin-2-yl-thiourea (PPT) are described. The electrodes exhibit a Nernstian slope of 20.2 +/- 0.8 (CGE) and 19.9 +/- 0.4 (PME) mV decade(-1) of activity in Fe3+ ion over a wide concentration range from 3.0 x 10(-7) to 1.0 x 10(-2) M for CGE and 6.9 x 10(-7) to 1.0 x 10(-2) M Fe3+ for PME. The lower detection limits by CGE and PME are 2.0 x 10(-7) and 3.9 x 10(-7) M. respectively, in the pH range of 1.8-5.6 for PME and 1.8-5.8 for CGE with a fast response time (< 10 s). The standard electrode potentials were determined at different temperatures and used to calculate the isothermal coefficient of the PME. The PME showed the working temperature range of 22-55 degrees C with isothermal temperature coefficient of 1.33 x 10(-3) V/degrees C and it was also used in non-aqueous solvents. The electrodes were successfully applied to determine iron(III) in water samples. (c) 2010 Elsevier Ltd. All rights reserved.