A novel Pentamethoxy Flavonol 'Cordiofolinol' (P3) has been isolated from anti-inflammatory activity guided fractionation of methanol extract of Haldina cordifolia stem Bark with a gradient of methanol in chloroform. Further P3 was screened for anti-inflammatory activity on carrageenan and dextran induced inflammation model in rats at the dose level of 50 mg/kg body weight. Treatment of inflammed rats with P3 has showed significant reduction in inflammation caused by carrageenan (P>0.01) and dextran (P>0.05). Hence P3 can be considered as the principle component responsable for the anti-inflammatory activity for Haldina cordifolia bark. The characterization of P3 was done by spectral studies like IR, 1H-NMR, 13C-NMR & mass spectroscopy. On the basis of spectral studies the structure of P3 has been elucidated as 5, 7, 3', 4', 5' –Pentamethoxy Flavonol. This is a novel Flavonol isolated from the bark of H. cordifolia for the first time and given a trival name Cordiofolinol.