BACKGROUND: DETERMINATION OF COPPER CONTENTS HAS GREAT IMPORTANCE DUE TO ITS WIDESPREAD APPEARANCE AND APPLICATION IN ENVIRONMENTAL SAMPLES. [1].THE ELECTROANALYTICAL PROCEDURES ARE PREFERRED DUE TO THEIR HIGH SENSITIVITY, SIMPLE OPERATION, AND LOW COST. THE POTENTIOMETRIC METHOD USING ION SELECTIVE electrodeS (ISES) BENEFIT FROM ADVANTAGES SUCH AS FAST, SIMPLE INSTRUMENTATION, ETC [2]. IN THIS RESEARCH, MULTIWALLED carbon NANOTUBES WERE Modified AND APPLIED FOR CONSTRACTION OF CPE. THE EFFECT OF SIGNIFICANT VARIABLES WAS INVESTIGATED AND OPTIMIZED. FINALLY, THE PERFORMANCE OF CU2+ - CPE WAS INVESTIGATED AND SUCCESSFULLY APPLIED FOR MONITORING THE CU2+ IONS CONTENT IN REAL SAMPLES.METHODS: MWCNTS WERE Modified BY CHEMICAL METHODS TO OBTAIN THE 3- METHOXY 2-((3-SILYLPROPYLIMINO) METHYL) PHENOL CHEMICALLY BONDED TO MWCNTS (MSPIMP-MWCNT) AND WERE CHARECTRIZED BY FT-IR AND OTHER RELATED TECHNIQUES AND IN THE MATRIX OF carbon paste APPLIED WITH OTHER INGREDIENTS SUCH AS (NATPB). THE MIXTURE IS HOMOGENIZED, LEFT AT ROOM TEMPERATURE TO EVAPORATE THF, THEN DIFFERENT AMOUNTS OF REAGENTGRADE GRAPHITE POWDER AND NUJOL OIL IS ADDED AND MIXED THROUGHLY AND THEN PACKED INTO THE HOLE OF THE electrode BODY.RESULTS: OPTIMUM COMPOSITION OF carbon paste WAS SET AS (NUJOL (9 DROP) AND GRAPHITE POWDER: NATPB: CARRIER IN THE MASS (MG) RATIO OF 150.9.60). IT WAS FOUND THAT CONSTRUCTION OF CPE AT ABOVE MENTION (SPECIFIED) CONDITION LEAD TO SIGNIFICANT ENHANCE IN THE SELECTIVITY AND SENSITIVITY TOWARD CU2+ IONS OVER A WIDE CONCENTRATION RANGE OF 4.09×10-8-1.0×10-2 MOL L-1 WITH DETECTION LIMIT OF 1.6×10-8 MOL L-1 AND A NERNSTIAN SLOPE OF 29.56±0.56 MV PER DECADE-1 OF CU2+ CONCENTRATION. THE electrode RESPONSE IS INDEPENDENT OF PH IN THE RANGE OF 3.5-5.5 WITH RESPONSE TIME LOWER THAN 20 S. THE POTENTIOMETRIC SELECTIVITY COEFFICIENTS OF PROPOSED CU2+ ION - CPE SHOW ITS MODERATE SELECTIVITY FOR CU2+ ION TOWARD OTHER METAL IONS. CONCLUSION: ON THE BASIS OF THE RESULTS DISCUSSED IN THIS PAPER, MSPIMP-MWCNT IS SUITABLE NEUTRAL CARRIER FOR THE CONSTRUCTION OF A carbon paste electrode FOR DETERMINATION OF CU2+ ION IN SOLUTION. THE PROPOSED electrode HAS GOOD OPERATION CHARACTERISTICS PERFORMANCE SUCH AS HIGH SENSITIVITY, STABILITY, RESPONSE TIME, DETECTION LIMIT AND WIDE LINEAR RANGE.