A regioselective one-step process for the synthesis of 2-hydroxyquinoxaline of Formula or tautomers thereof: comprising reacting 1,2-phenylenediamine of Formula : with an excess amount of glyoxylic acid, glyoxylic acid monohydrate, or a 2,2-dialkoxyacetatic of Formula : at a low temperature ranging from -20°C to 5°C; wherein R 1 is selected from the group consisting of NO 2 , CN, CO 2 R 4 , CONR 5 R 6 , CF 3 , and halogen; R 2 is selected from the group consisting of hydrogen, alkyl, and halogen; R 3 is C 1 -C 3 alkyl; or two R 3 groups, together with the oxygen atoms to which they are bound, form a 5-, 6-, or 7-membered O-containing heterocyclic ring; R 4 is C 1 -C 6 alkyl, optionally substituted with one or more groups selected from the group consisting of halogen, R', OR', and SR'; or represents C 3 -C 6 cycloalkyl, C 6 -C 10 aryl, or C 7 -C 12 arylalkyl, all of which being optionally substituted by one or more groups selected from the group consisting of halogen, R', OR', and SR'; R 5 and R 6 , which can be the same or different, are independently selected from the group consisting of hydrogen, C 1 -C 6 alkyl, C 6 -C 10 aryl, and C 7 -C 12 arylalkyl; or R 5 and R 6 , together with the nitrogen atom to which they are bound, form a 5-, 6-, or 7-membered N-containing heterocyclic ring; and R' is alkyl, wherein a 1,2-phenylenediamine of Formula is provided in the form of a solution with a suitable solvent; and wherein glyoxylic acid, glyoxylic acid monohydrate, or a 2,2-dialkoxyacetic acid of Formula is provided in the form of a solution with a suitable solvent, and the solution of a 1,2-phenylenediamine of Formula is added into the solution of glyoxylic acid, glyoxylic acid monohydrate, or a 2,2-dialkoxyacetic acid of Formula , and wherein the excess amount of glyoxylic acid, glyoxylic acid monohydrate, or a 2,2-dialkoxyacetic acid of Formula is at least 3 molar equivalents relative to per molar equivalent of a 1,2-phenylenediamine of Formula . at a low temperature ranging from -20°C to 5°C; wherein R 1 is selected from the group consisting of NO 2 , CN, CO 2 R 4 , CONR 5 R 6 , CF 3 , and halogen; R 2 is selected from the group consisting of hydrogen, alkyl, and halogen; R 3 is C 1 -C 3 alkyl; or two R 3 groups, together with the oxygen atoms to which they are bound, form a 5-, 6-, or 7-membered O-containing heterocyclic ring; R 4 is C 1 -C 6 alkyl, optionally substituted with one or more groups selected from the group consisting of halogen, R', OR', and SR'; or represents C 3 -C 6 cycloalkyl, C 6 -C 10 aryl, or C 7 -C 12 arylalkyl, all of which being optionally substituted by one or more groups selected from the group consisting of halogen, R', OR', and SR'; R 5 and R 6 , which can be the same or different, are independently selected from the group consisting of hydrogen, C 1 -C 6 alkyl, C 6 -C 10 aryl, and C 7 -C 12 arylalkyl; or R 5 and R 6 , together with the nitrogen atom to which they are bound, form a 5-, 6-, or 7-membered N-containing heterocyclic ring; and R' is alkyl, wherein a 1,2-phenylenediamine of Formula is provided in the form of a solution with a suitable solvent; and wherein glyoxylic acid, glyoxylic acid monohydrate, or a 2,2-dialkoxyacetic acid of Formula is provided in the form of a solution with a suitable solvent, and the solution of a 1,2-phenylenediamine of Formula is added into the solution of glyoxylic acid, glyoxylic acid monohydrate, or a 2,2-dialkoxyacetic acid of Formula , and wherein the excess amount of glyoxylic acid, glyoxylic acid monohydrate, or a 2,2-dialkoxyacetic acid of Formula is at least 3 molar equivalents relative to per molar equivalent of a 1,2-phenylenediamine of Formula . <EOS>