A process for preparing lithium hydroxide, said process comprising: submitting an aqueous composition comprising lithium sulfate and/or lithium bisulfate to a first electromembrane process that comprises a two-compartment membrane process in a first electrochemical cell, said cell comprising an anolyte compartment separated from a catholyte compartment by a cation exchange membrane, under suitable conditions for conversion of said lithium sulfate and/or lithium bisulfate to lithium hydroxide, and obtaining a first lithium-reduced aqueous stream and a first lithium hydroxide-enriched aqueous stream; measuring pH of said first lithium-reduced aqueous stream in the anolyte compartment of said first electrochemical cell; when said pH of said first lithium-reduced aqueous stream decreases below a pre-determined value, transferring said first lithium-reduced aqueous stream from said anolyte compartment of said first electrochemical cell to a central compartment of a second electrochemical cell, said cell comprising an anolyte compartment separated from a central compartment by an anion exchange membrane and a catholyte compartment separated from said central compartment by a cation exchange membrane, submitting said first lithium-reduced aqueous stream to a second electromembrane process that comprises a three-compartment membrane process in said second electrochemical cell, under suitable conditions to prepare at least a further portion of lithium hydroxide and obtaining a second lithium-reduced aqueous stream and a second lithium-hydroxide enriched aqueous stream, and optionally measuring pH of said second lithium-reduced aqueous stream in said central compartment of said second electrochemical cell, and transferring said second lithium-reduced aqueous stream from said central compartment of said second electrochemical cell to said anolyte compartment of said first electrochemical cell when said pH of said first lithium-reduced aqueous stream in said second electrochemical cell is above a pre-determined value, wherein said anolyte compartment of said first electrochemical cell and said central compartment of said second electrochemical cell are in fluid flow communication with one another for conveying lithium sulfate and/or lithium bisulfate. submitting an aqueous composition comprising lithium sulfate and/or lithium bisulfate to a first electromembrane process that comprises a two-compartment membrane process in a first electrochemical cell, said cell comprising an anolyte compartment separated from a catholyte compartment by a cation exchange membrane, under suitable conditions for conversion of said lithium sulfate and/or lithium bisulfate to lithium hydroxide, and obtaining a first lithium-reduced aqueous stream and a first lithium hydroxide-enriched aqueous stream; measuring pH of said first lithium-reduced aqueous stream in the anolyte compartment of said first electrochemical cell; when said pH of said first lithium-reduced aqueous stream decreases below a pre-determined value, transferring said first lithium-reduced aqueous stream from said anolyte compartment of said first electrochemical cell to a central compartment of a second electrochemical cell, said cell comprising an anolyte compartment separated from a central compartment by an anion exchange membrane and a catholyte compartment separated from said central compartment by a cation exchange membrane, submitting said first lithium-reduced aqueous stream to a second electromembrane process that comprises a three-compartment membrane process in said second electrochemical cell, under suitable conditions to prepare at least a further portion of lithium hydroxide and obtaining a second lithium-reduced aqueous stream and a second lithium-hydroxide enriched aqueous stream, and optionally measuring pH of said second lithium-reduced aqueous stream in said central compartment of said second electrochemical cell, and transferring said second lithium-reduced aqueous stream from said central compartment of said second electrochemical cell to said anolyte compartment of said first electrochemical cell when said pH of said first lithium-reduced aqueous stream in said second electrochemical cell is above a pre-determined value, wherein said anolyte compartment of said first electrochemical cell and said central compartment of said second electrochemical cell are in fluid flow communication with one another for conveying lithium sulfate and/or lithium bisulfate.