The ferroelectric crystals of Glycine Phosphite were grown by low temperature solution growth technique. The variation of hardness on (010) plane of monoclinic GPI crystals, (NH3CH2COOH3PO 3), with load was studied. Vickers hardness, Hv and Knoop hardness numbers, Hk were found to decrease with an increase in load. Meyer's index 'n' was found to be less than 2 showing soft-material characteristics. The fracture toughness values 'Kc', determined from measurements of crack lengths, were estimated to be 0.1266 MN/m3/2, The brittleness indices 'Bi' were estimated as 4270.7 m -1/2. Elastic stiffness coefficient, C11 and Young's modulus were calculated from the hardness. © 2010 Taylor & Francis Group, LLC.