The surface termination and geometric structure of molecular beam epitaxially (MBE)-grown HgSe(001) has been studied by means of X-ray photoelectron spectroscopy (XPS) and high-resolution low-energy electron diffraction. The surface exhibit a c(2 x 2) reconstruction and is terminated by Ng. In addition, the valence band offset of the HgSe/CdSe(001) heterostructure has been investigated by k-resolved ultraviolet photoemission (UPS). Special care was taken to determine the true position of the VB maximum in the Brillouin zone (Gamma-point) by using Ar-I excitation during the angle-dependent UPS measurements. Thus, the valence band discontinuity was determined as 0.58 +/- 0.05 eV, This value and recent results for the HgTe/CdTe heterojunction support the trend expected by theory predicting a larger Delta E-VBO for selenides than for tellurides.