A method for manufacturing a predetermined quantity of a batch of liquid acid concentrate for hemodialysis machines, in particular for manufacturing batches of at least 100 I, preferably of at least 1,000 I, which method consists of the following steps: Preliminary step: Connection to a mixing tank of - a water source, - an acid source, - a sodium chloride source, - an electrolyte tank containing a mixture of the electrolytes potassium and/or calcium and/or magnesium in exactly the quantity needed for the manufacture of the batch of liquid acid concentrate, wherein said electrolyte mixture may contain, in addition, at most one part of the acid and/or at most one part of the sodium chloride needed for the manufacture of the batch of liquid acid concentrate; Step a): Introduce the quantity of water needed for the manufacture of the batch of liquid acid concentrate into the mixing tank; Step b): Introduce the quantity of acid needed for manufacture the batch of liquid acid concentrate into the mixing tank, taking into account the quantity of acid that may be present in the electrolyte tank; Step c): Repeat following sub-steps until the electrolyte mixture contained in the electrolyte tank is completely dissolved: Sub-step c1) transfer part of the solution contained in the mixing tank into the electrolyte tank, then Sub-step c2) transfer the solution contained in the electrolyte tank into the mixing tank, leaving the still solid constituents in the electrolyte tank; Step d): Introduce the quantity of sodium chloride needed to manufacture the batch of liquid acid concentrate into the mixing tank, taking into account the quantity of sodium chloride that may be present in the electrolyte tank; Step e): Stir and recirculate the solution by extracting it from a point in the mixing tank and reintroducing it at another point until a homogeneous liquid acid concentrate is obtained; wherein Steps a) to d) can be performed in any order, Step a) preceding always Step c). Preliminary step: Connection to a mixing tank of - a water source, - an acid source, - a sodium chloride source, - an electrolyte tank containing a mixture of the electrolytes potassium and/or calcium and/or magnesium in exactly the quantity needed for the manufacture of the batch of liquid acid concentrate, wherein said electrolyte mixture may contain, in addition, at most one part of the acid and/or at most one part of the sodium chloride needed for the manufacture of the batch of liquid acid concentrate; - a water source, - an acid source, - a sodium chloride source, - an electrolyte tank containing a mixture of the electrolytes potassium and/or calcium and/or magnesium in exactly the quantity needed for the manufacture of the batch of liquid acid concentrate, wherein said electrolyte mixture may contain, in addition, at most one part of the acid and/or at most one part of the sodium chloride needed for the manufacture of the batch of liquid acid concentrate; Step a): Introduce the quantity of water needed for the manufacture of the batch of liquid acid concentrate into the mixing tank; Step b): Introduce the quantity of acid needed for manufacture the batch of liquid acid concentrate into the mixing tank, taking into account the quantity of acid that may be present in the electrolyte tank; Step c): Repeat following sub-steps until the electrolyte mixture contained in the electrolyte tank is completely dissolved: Sub-step c1) transfer part of the solution contained in the mixing tank into the electrolyte tank, then Sub-step c2) transfer the solution contained in the electrolyte tank into the mixing tank, leaving the still solid constituents in the electrolyte tank; Step d): Introduce the quantity of sodium chloride needed to manufacture the batch of liquid acid concentrate into the mixing tank, taking into account the quantity of sodium chloride that may be present in the electrolyte tank; Step e): Stir and recirculate the solution by extracting it from a point in the mixing tank and reintroducing it at another point until a homogeneous liquid acid concentrate is obtained; wherein Steps a) to d) can be performed in any order, Step a) preceding always Step c).