a b s t r a c tA simple, sensitive and selective fluorescent chemo dosimeter rhodamine B phenyl hydrazide (RBPH) for Cu 2 þ was proposed. This probe is non fluorescent and colorless but exhibits fluorescent enhancement at 580 nm and displayed color change from colorless to pink for Cu 2 þ in the pH range 1-6. Fluorescence microscope experimental results reveals that this chemo sensor is cell permeable and can be used for fluorescence imaging of Cu 2 þ ions in living cells. This probe can detect Cu 2 þ with good linear relationships from 10 to 100 nM with r ¼0.99971 then limit of detection was found to be 0.015 nM with 7 0.91% RSD at 10 nM concentrations.