The effects of various flours on production of thermostable beta -amylase and pullulanase using Clostridium thermosulfurogenes SV2 was studied in submerged fermentation. Among the flours added to PYE basal medium, potato flour was the best substrate for enzyme production, and under optimal conditions C. thermosulfurogenes SV2 produced 0.87 and 0.98 U of thermostable beta -amylase and pullulanase, respectively, per ml culture broth.