A 3-kDa membrane bioreactor (with a downstream ultrafiltration module equipped with a ceramic membrane) was tried in one- and two-step enzymatic (alpha-amylase and balanced glucoamylase-pullulanase) hydrolyses of oxidized potato starch, acetylated potato starch, and sodium salt of starch octenylsuccinate. In 1 hr. of the one-step process, the permeate fell by 10%; in two-step, by 20% at 0.1 MPa trans-membrane pressure. The products revealed a desired deg. of saccharification. The sepn. properties of the membrane, the amt. of the enzyme used, and the type of modified starch affected the process.