From the binary systems M(2)SO(4)/H2SO4 (M = Ba, Sr), two new hydrogen sulfates, (Ba(HSO4)(2)(H2SO4)(3) and Sr(HSO4)(2)(H2SO4), have been synthesized and structurally characterized. Ba(HSO4)(2)(H2SO4)(3) crystallizes in the orthorhombic space group P2(1)2(1)2(1) with unit cell parameters a=4.680(1), b=11.267(2), c=29.188(6)Angstrom, Z=4. BaO9 trigonal prismatic polyhedra with Ba-O distances of 2.68-3.02 Angstrom from nine different SO4 tetrahedra are connected via common bases and build ''isolated'' columns consisting of O-S-O bridged double chains along the x-axis. HSO4 and H2SO4 tetrahedra are linked via hydrogen bonds to form columns. Sr(HSO4)(2)(H2SOr) crystallizes in the triclinic space group P (1) over bar with unit cell parameters a=5.971(1), b=8.468(2), c=10.226(2)Angstrom, alpha=8.171(3), beta=83.30(3), gamma=70.69(3)degrees, Z=2. Sr is coordinated by nine oxygen atoms from seven different SO4 tetrahedra with Sr-O distances of 2.47-2.84 Angstrom. The SrO9 polyhedra build layers consisting of O-S-O bridged chains. Three crystallographically different SO4 tetrahedra are linked via hydrogen bonds to form a kind of flattened cylinder along the x-axis.