Abstract: The invention relates to an electrodialysis device for the desalination of water for oil and gas applications comprising: a membrane stack comprising alternating cation- and anion-exchange membranes (2.1, 2.3) and a plurality of spacers (2.2, 2.4), each spacer being arranged between two successive membranes; wherein at least one of the spacers (2.2, 2.4) comprises a recessed area (3.2) and a non-recessed area (3.3), a central opening (3.1) within the recessed area (3.2); the spacer (2.2, 2.4) is provided with at least four orifices (3.4, 3.5) within the non-recessed area (3.3); and with respective channels (3.6) which connect at least two of the orifices (3.4) with the central opening (3.1); and one membrane (2.1, 2.3) is accommodated in the recessed area (3.2). The invention also relates to a water desalination process using the electrodialysis device mentioned above.