A process is described of producing an MTT framework type molecular sieve by crystallizing a mixture capable of forming said molecular sieve, wherein the mixture comprises sources of alkali or alkaline earth metal (M), an oxide of trivalent element (X), an oxide of tetravalent element (Y), water and a directing agent (R) of the formula (CH3)3N+CH2CH2CH2N+(CH3)2CH2CH2CH2N+(CH3)3, and has a composition, in terms of mole ratios, within the following ranges. YO2/X2O3less than 45 H2O/YO25 to 100 OH−/YO20.05 to 0.5 M/YO20.05 to 0.5 and R/YO2>0 to