A new process for trehalose production from starch was developed using a novel glycosyltransferase and a novel alpha-amylase from Sulfolobus solfataricus KM1. The yield of trehalose from starch was 81.5% using the two enzymes and a thermostable debranching enzyme. Trehalose production was carried out at high temperature over 60 degrees C and at a high concentration of starch with no risk of contamination bg microorganisms or retrogradation of starch.