The spectral parameters of Nd3+ ions in Nd3+:Klu(WO4)2 crystal were calculated based on Judd-Ofelt theory and obtained as follows: for the oscillator strengths ?λ: ?2 = 7.5029×10-20 cm2, ?4 = 7.1837×10-20 cm2 and ?6 = 3.1189×10-20 cm2; the radiative lifetime is 123 μs; the quantum efficiency is equal to 64.55%; and β1 = 0.5498, β2 = 0.3943, β3 = 0.0551 and β4 = 0.0027 for the fluorescence branch ratios. The spectral parameters of Nd3 + ions in Nd3 +: Klu (WO4) 2 crystals were calculated based on Judd-Ofelt theory and obtained as follows: for the oscillator strengths?:? 2 = 7.5029 × 10-20 cm2,? 4 = 7.1837 × 10-20 cm2 and? 6 = 3.1189 × 10-20 cm2; the radiative lifetime is 123 μs; the quantum efficiency is equal to 64.55%; and β1 = 0.5498, β2 = 0.3943, β3 = 0.0551 and β4 = 0.0027 for the fluorescence branch ratios.