The interaction between ligand N-[(E)-1-(3, 5-dichloro-2-hydroxy-phenyl)ethylideneamino]-2-oxo-chromene-3-carboxamide, N-[(E)-1-(2-hydroxy-5-methyl-phenyl)ethylideneamino]-2-oxo-chromene-3-carboxamide and Fe(III), Mn(II) metal ion. The Bjerrum-Calvin titration technique as modified by Irving and Rossotti is used in this work. In this system, the separation of the acid-ligand curve from the acid-ligand and metal curve explains the formation of the complexes. The complex formation is explained through the half-integral method and point-wise calculation method.