Supercapacitors are promising energy storage devices because of fast charge and discharge capacity, long lifetime and high power sources when compared to conventional batteries. Most carbon based supercapacitors nowadays use organic or ionic liquid based electrolytes in order to benefit from the large potential window in those solvents thus enabling more energy storage. However the devices suffer from low ionic mobility in such electrolytes, and also from economical, safety and environmental concerns associated with the use of organic solvents. Boron doped diamond (BDD) features a wide potential window in aqueous electrolytes and high stability toward oxidation in acidic or alkaline media, and therefore offers the possibility for BDD electrodes supercapacitor to operate in water. Here highly porous diamond electrodes fabricated by microwave plasma chemical vapor deposition of BDD over a conductive polypyrrole template with high double layer capacitance around 3 mF.cm-2 were mounted in symmetrical pouch cell supercapacitor using either 1M H 2 SO 4 or 1M TEABF 4 in propylene carbonate electrolytes. The performances of both devices were investigated. Energy and power values close to 1 µWh.cm-2 and 700 µW.cm-2 were recorded in water, thus surpassing by almost one order of magnitude the energy storage performances of the device using organic electrolyte. Highlights  A symmetrical pouch cell supercapacitor was fabricated using a highly porous diamond electrode material, grown over a polymer template on four inches substrates, and featuring a capacitance of 3 mF.cm-2  The performances of the device were compared when using either an aqueous or organic based electrolytes  Energy and power values close to 1 µWh.cm-2 and 700 µW.cm-2 were recorded in water, thus surpassing by almost one order of magnitude the energy storage performances of similar carbon based devices using organic or ionic liquid electrolytes.