The position of H atom in the crystal K2H(IO3)2C1 was determined by neutron diffraction. 481 refletions were collected including 355 independent ones. Both programs of SHELX and OR XFLS4 were used to perform Fourier and difference Fourier syntheses and the least square refinement (with isotropic and anisotropic extinction correction). The final R value was 3.3%. The results make sure of the existence of the hydrogen bond in the crystal.