Single crystals of potassium acid phthalate (KAP), Nickel Doped KAP (NiKAP) and Cobalt doped KAP(Co KAP) have been grown from aqueous solutions by solvent evaporation method. The effect of these metal irons on surface morphology, structure, optical and mechanical properties have been studied. Single crystal XRD studies of these crystals confirm that both the added impurities have modified the structure of the KAP crystals in a similar manner. The presence of dopants in the crystal lattice have been further confirmed by FTIR analysis. The stoichiometric composition of both the doped crystals have been studied using EDAX analysis. Optical absorbance was carried out for all the crystals. The absorbance in the visible region observed in both the doped crystals was assigned to their d-d transitions. Micro hardness of the pure and doped crystals were found using Vickers?s Hardness Technique.