Europium oxyhydroxide crystals were synthesized by the flux method. The as-grown crystals were transparent and had a plate-like shape with natural flat surfaces. The powder XRD data were refined by assuming a monoclinic structure of the space group P21/m and lattice parameters of a=0.4346 nm, b=0.3744 nm, c=0.6107 nm, and β=108.62°. The magnetic susceptibility of the EuOOH crystals exhibited typical Van Vleck temperature-independent paramagnetism below 120 K. The calculated susceptibility, based on Van Vleck’s theory, agreed with the experimental data to some extent, with the coupling constant λ=458±10 K. The experimental results were in close agreement with the results calculated using a modified formula with λ=505±2 K and a constant term C=4.6×10-4 emu/(mol·Oe). Europium oxyhydroxide crystals were synthesized by the flux method. The as-grown crystals were transparent and had a plate-like shape with natural flat surfaces. The powder XRD data were refined by assuming a monoclinic structure of the space group P21 / m and lattice parameters of a = 0.4346 nm, b = 0.3744 nm, c = 0.6107 nm and β = 108.62 ° The magnetic susceptibility of the EuOOH crystal exhibited typical Van Vleck temperature-independent paramagnetism below 120 K. The calculated susceptibility, based on Van Vleck’s theory , agreed with the experimental data to some extent, with the coupling constant λ = 458 ± 10 K. The experimental results were in close agreement with the results calculated using a modified formula with λ = 505 ± 2 K and a constant term C = 4.6 × 10 -4 emu / (mol · Oe).