Potassium dihydrogen phosphate (KDP) is a well known non–linear optical (NLO) material for various optoelectronics applications. In this study pure and doped KDP crystals have been grown by Slow Evaporation Solution Growth Technique at constant temperature. The effect of dopants on the growth and characterization of KDP crystals has been studied. KDP is doped with ammonium compounds such as Ammonium chloride and ammonium bromide at three different concentrations depending upon its molarity. The crystallinity and cell parameters were characterized by x-ray diffraction analysis, the shifting in frequency assignment of different functional groups of KDP due to the addition of dopants were analysed by FTIR analysis. The enhancement in transmittance of grown KDP crystals with the inclusion of dopants was determined by UV visible spectral analysis and the results have been depicted with suitable discussions.