In this Present investigation is attempted to make a methodical elucidations of the complex formation of Cu (II)ions
with the pyrazole derived from 3(4-nitrophenyl)-4-benzoyl 5(2-hydroxy-4-bromo-phenyl) pyrazole and 3(4-chlorophenyl)-4-
benzoyl 5(2-hydroxy-4-nitro-phenyl) pyrazole.The stability constants of their complexes with Cu (II) ions, have been studied by
using Irving-Rossotti method at constant temperature 300K and ionic strength 0.01 M.