Single crystals of ammonium dihydrogen phosphate (ADP) mixed with different mole concentrations of thiourea were grown using slow evaporation solution technique at 30 degrees C. In order to study the effect of mixing thiourea on the structural characteristics of ADP, X-ray diffraction studies were carried out on the crystals using Shimadzu X-ray diffractometer with Cu K alpha radiation. X-ray study revealed that the structures of the thiourea-mixed ADP are slightly distorted compared to the pure ADP crystal structure. Inclusion of thiourea enhances the growth of ((1) over bar 00) plane of the ADP crystal. Thiourea-mixed ADP crystals were found to have maximum inclusion, as the thiourea concentration was 10 mol%. (c) 2006 Elsevier B.V. All rights reserved.