The curing behavior of diglycidyl ether of bisphenol-A (DGEBA) with different phosphorus containing diamidediimide- tetraamines (DADITAs) was studied by DSC. Eight DADITAs of varying structures were synthesized by reacting 1 mole of pyromellitic anhydride (PMDA)/3

3′-benzophenone tetracarboxylic dianhydride (BTDA)/1

4

5

8-naphthalene tetracarboxylic dianhydride (NTDA)/4

4′-oxydiphthalic anhydride (ODPA) with 2 mole of L-tryptophan (T) in a mixture of acetic acid and pyridine (3:2

V/V

) followed by activaton with thionyl chloride and then condensation with excess of phosphorus containing triamines tris(3-aminophenyl) phosphine (TAP) and tris(3-aminophenyl) phosphine oxide (TAPO). DADITAs obtained by reacting PMDA/BTDA/NTDA/ODPA with L-tryptophan followed by condensation with TAP/TAPO were designated as PTAP

PTAPO

BTAP

BTAPO

NTAP

NTAPO

OTAP and OTAPO respectively. The structural characterization of synthesized DADITAs was done by FTIR

1

H-NMR

13

C-NMR

31

P-NMR spectroscopic techniques and elemental analysis. Thermal stability of the isothermally cured epoxy was investigated using dynamic thermogravimetry analysis. The glass transition temperature (

T

g

) was highest in DGEBA cured using PTAP. All epoxy thermosets exhibited excellent flame retardancy

moderate changes in

T

g

and thermal stability. Due to presence of phosphorus in curing agents

all epoxy resin systems met the UL-94 V-0 classification and the limiting oxygen index (LOI) reached up to 38.5

probably because of the nitrogen-phosphorus synergistic effect.