N1,N2-Bis [1-(2-hydroxyphenyl)methylidene]ethanedihydrazide (MEH) was used as new compound which plays the role of an excellent ion carrier in the fabrication of a Ho(Ⅲ) membrane electrode. The electrode shows a good selectivity for Ho(Ⅲ) ion with respect to most common cations including alkali, alkaline earth, transition and heavy metal ions. This electrode has a wide linear dynamic range from 1.0 x 10-6 to 1.0 x 102 mol/L with a Nernstian slope of 19.8 ± 0.3 mV per decade and a low detection limit of 5.8 x 10-7 mol/L in the pH range of 2.5-9.8, while the response time was rapid (