A kind of novel n = 2 phthalonitrile oligomer containing biphenyl ethernitrile (2PEN-BPh) had been firstly synthesized from 2,6-dichlorobenzonitrile, 4,4'-biphenol and 4-nitrophthalonitrile via solution reaction, and the 2PEN-BPh was characterized by FTIR, H-1-NMR spectra which exhibited that cyano groups and ethernitrile linkages existed in the backbone of 2PEN-BPh. The 2PEN-BPh oligomer was blended with bisphthalonitrile monomer, the curing reaction behaviors of the blends were studied by FTIR, DSC, and rheological analysis. The thermal and thermo-oxidative stabilities of the 2PEN-BPh/BPh polymers were investigated by TGA, and the results showed that the completely cured polymers could achieve char yields up to 78% at 800 degrees C in nitrogen, above 11% at 800 degrees C in air. The whole research indicated that the 2PEN-BPh/BPh blends could efficiently improve the processability of BPh monomer without scarifying other desirable high temperature properties. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 882-887, 2011