We demonstrate quasi-vertical reverse blocking (RB) MOSFETs on 6.7 mu m thick GaN grown on a 6 inch Si substrate by metalorganic chemical vapor deposition. The RB capability was achieved by replacing the ohmic drain with a quasi-vertical Schottky drain, resulting in a RB voltage of similar to 300 V while preserving the ON-resistance (R-on,R-sp). Schottky contacts on etched i-GaN surface were realized through an optimized fabrication process based on tetramethylammonium hydroxide treatments. The fabricated RB-MOSFET had a low R-on,R-sp of 4.75 m omega cm(2), current density of similar to 0.9 kA cm(-2) and a forward blocking voltage of 570 V.