This protein labeling kit comprises our superior near-IR fluorescent dye CF750 in succinimidyl ester form and all other reagents required for labeling 3×1 mg antibody. CF750 has an absorption peak at 755 nm and emission peak at 777 nm. CF750 is 30-40% brighter than Alexa Fluor? 750 and at least twice as bright as Cy?7. Also, importantly, CF750 is much more photostable than Cy?7 and Alexa Fluor? 750. Like our other near-IR CF dyes, CF750 is ideal for in vivo imaging, near-IR Western blotting and flow cytometry. Because of the superior brightness of CF750, antibodies labeled with the dye can be used in flow cytometry using 633 nm excitation and yield higher signal than antibodies labeled with tandem dyes.