Abstract Two microporous zinc–gallium phosphates (CN 3 H 6 )[ZnGaP 2 O 8 ] ( I ) and (C 4 NH 10 )[ZnGaP 2 O 8 ] ( II ) have been synthesised under solvothermal conditions in the presence of guanidinium chloride and pyrrolidine respectively. The structure of ( I ) has been determined by single-crystal X-ray diffraction [monoclinic, I 2/ a , a =10.041(1), b =9.220(1), c =10.469(2) A, β =91.60(1)°, V =969.20 A 3 , Z =8 at 150 K]. Compound ( II ), prepared as a pure polycrystalline powder [orthorhombic, Fddd , a =9.993(4), b =14.525(5), c =15.028(7) A at 293 K], is isostructural with the previously reported material (C 4 NH 10 )[CoGaP 2 O 8 ]. Although the ZnGaPO materials have the same framework topology as the zeolite gismondine, they have very different cage structures, reflecting the different sizes and hydrogen bonding abilities of the resident guanidinium and pyrrolidinium cations.