A gene encoding a GH10 endo-xylanase from Geobacillus sp. WSUCF1 was cloned and expressed in Escherichia coli. Recombinant endo-xylanase (37 kDa) exhibited high specific activity of 461.0 U/mg of protein. Endo-xylanase was optimally active on birchwood xylan at 70 degrees C and pH 6.5. The endo-xylanase was found to be highly thermostable at 50 and 60 degrees C, retaining 82% and 50% of its original activity, respectively, after 60 h. High xylan conversions (92%) were obtained with oat-spelt xylan hydrolysis. Higher glucan and xylan conversions were obtained on AFEX-treated corn stover with an enzyme cocktail containing WSUCF1 endo-xylanase (71% and 47%) as compared to enzyme cocktail containing commercial fungal endo-xylanase (64% and 41%). High specific activity, active at high pH's, wide substrate specificity, and higher hydrolytic activity on recalcitrant lignocellulose, make this endo-xylanase a suitable candidate for biofuel and bioprocess industries. (C) 2014 Elsevier Ltd. All rights reserved.