Four novel diamides of squaric acid were synthesized in high yields using a condensation reaction of methioninamide esteramide of squaric acid with different amides of amino acids. Newly synthesized compounds were investigated by elemental analyses, IR and NMR. The molecular structures of the compounds were elucidated by a DFT method. The theoretical analysis showed that squaric fragment and NH-groups lied in one plane which was almost perpendicularly oriented to the plane of asymmetric C-atom.