In enzymology, a maltose synthase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are alpha-D-glucose 1-phosphate and H<sub>2</sub>O, whereas its two products are maltose and phosphate.
This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is alpha-D-glucose-1-phosphate:alpha-D-glucose-1-phosphate 4-alpha-D-glucosyltransferase (dephosphorylating).