Three new, mixed-valent layered vanadyl phosphates, Ag0.43VOPO4. 2H(2)O (AgVPO), Cu0.16VOPO4. 2.5H(2)O (CuVPO), and Zn0.11VOPO4. 2.5H(2)O (ZnVPO), have been synthesized hydrothermally and their structures determined by single-crystal X-ray diffraction : AgVPO is triclinic, space group P (1) over bar, a = 6.287(1), b = 6.283(1), and c = 13.240(1) Angstrom, alpha = 80.98(1), beta = 86.58(1) and gamma = 90.00(1)degrees, Z = 4; CuVPO is triclinic, space group P (1) over bar, a = 6.260(2), b = 6.249(3), and c = 7.257(1) Angstrom, alpha = 83.62(3), beta = 73.99(2), and gamma = 90.13(4)degrees, Z = 2; ZnVPO is triclinic, space group P (1) over bar, a = 6.252(1), b = 6.248(2), and c = 7.339(3) A, alpha = 83.24(4), beta = 73.93(2), and gamma = 90.00(2)degrees, Z = 2. The structures are related to that of VOPO4. 2H(2)O. Metal powders have been found to be effective both as reductants and as countercations.