In the present paper, we report crystal structures of four types ([A(1)H][A(2)H]Y, [A(1)H]3[A(2)H]Y2, A(1)H[A(2)H···A(2)]Y, and A(1)H[A(1)H···A(2)]Y) mixed salts containing sulfate anion (Y = SO42−) amino acids A, i.e., sarcosine (Sar), dimethylglycine (DMG), betaine (Bet), β-alanine (β-Ala), l-proline (l-Pro): (β-AlaH)(DMGH)SO4·2H2O (I), (β-AlaH)(BetH)SO4 (II), (β-AlaH)(l-ProH)SO4 (III), (BetH...