[en] Experimental and theoretical investigation into magnetic susceptibility of pure beryllium monocrystals and Besub(100-x)Cusub(x) (with x=0.54 and x=1.34) alloys in the 77-1500 K temperature range is carried out. Noticeable decrease of diamagnetism of susceptibility component kappasub(parallel) with temperature growth is established, and transformation of diamagnetic extremum in kappasub(perpendicular)(T) in beryllium-copper alloys is also studied. Quantitative description of temperature dependences of susceptibility components kappasub(parallel) and kappasub(perpendicular) in the investigated samples is obtained within the frames of the suggested theory of beryllium magnetism based on the results of calculation of Be zonic structure and data on electron Be(Cu) spectrum