Acetylxylan esterase (AXE) catalyzes the hydrolytic cleavage of the ester bond between acetic acid and hemicellulose in plant cell walls. A putative AXE gene exhibiting high homology to carbohydrate esterase family 3 was found in the genome database of the fungusTalaromyces cellulolyticus(formerly known asAcremonium cellulolyticus). A truncated form of the protein, the catalytic domain of the enzyme, was prepared and crystallized. The best crystal was obtained at 293 K using 0.17 Mammonium sulfate, 28% PEG 4000, 5%(v/v) glycerol, 0.5%(w/v)n-octyl-β-D-glucoside. X-ray diffraction data were collected to 1.50 Å resolution. The crystal belonged to space groupP41212 orP43212, with unit-cell parametersa= 70.90,b= 70.90,c= 87.09 Å. One enzyme molecule per asymmetric unit gave a crystal volume per protein mass (VM) of 2.62 Å3 Da−1and a solvent content of 53.0%(v/v).