Hydrothermal treatment of an aqueous solution containing tetramethoxysilane, boric acid and ethylenediamine (EN) led to the crystallization of B-MFI (BOR-C) together with small amounts of B-ferrierite. A single-crystal X-ray diffraction study was performed on two small prismatic crystals of BOR-C with the unit cell dimensions: a=19.869(2), b=19.661(3), c=13.207(2) Å, V=5159.2 Å3, and a=19.875(1), b=19.669(1), c=13.218(2) Å, V=5167.2 Å3 (space group Pnma) using a laboratory diffractometer equipped with a CCD detector and a synchrotron radiation source, respectively. In both cases the unit cell volume and the B/Si occupancy agree with about 15% substitution of B for Si in the framework T-sites, corresponding to 14±1 B/u.c. Three independent EN molecules were located, one (EN1) is located in the sinusoidal 10-ring channel parallel to the [100] direction, lying on the (010) plane, the other two (EN2 and EN3) in the straight 10-ring channel. The negative charge of the framework is counterbalanced by the EN molecules in the form of divalent cations.