Crystal forms of O-desmethylvenlafaxine fumarate

The crystalline Form N of O-desmethylvenlafaxine fumarate, characterized by data selected from:

• a powder XRD pattern with peaks at about 9.5, 13.2, 14.6, 21.8 and 24.8° 2θ±0.2° 2θ;
• a powder XRD pattern as depicted in FIG. 1, a 13C NMR spectrum having signals at about 167.87, 131.33 and 114.43±0.2 ppm;
• a solid state 13C NMR spectrum as depicted in FIG. 4, or combinations thereof.