An experimental procedure adopted to prepare the recent Ferroelectric Glycine Phosphite (GPI) single crystal is presented. As the crystal solubility in water depends on temperature, single crystals were grown from fine seed crystals in a saturated solution by employing the slow cooling technique. Transparent, colourless crystals with habit morphology weighing about 8 gm were obtained with in a month. The same procedure was used to grow single crystals with Thiourea doped GPI (TUGPI). Powder X-ray diffraction studies as well as FTIR studies were carried out on both the crystals. The results are discussed in detail.