The mechanical behavior of aluminum honeycombs subjected to quasi-static combined compression-shear loading was experimentally investigated. Two different deformation patterns were observed, deforming cell walls non-inclined (Mode I) and inclined (Mode II) respectively. For the first time, normal and shear forces of honeycombs deforming in Mode II were measured directly using a tri-axial load cell. It was found that the shear force behavior was very different for Modes I and II, with a negative shear force being observed for Mode II, which was not previously reported. Three aluminum hexagonal honeycombs with different cell configurations (cell size and wall thickness) were tested at two loading velocities of 5 × 10⁻⁴ and 5 × 10⁻³ m/s, three loading angles of 15°, 30° and 45°, in the two plane orientations, respectively. The effects of loading velocity, loading angle and loading plane were discussed in detail. An empirical model specifically revealing the effect of loading angle on normal plateau stress was proposed. Initial yield surface was estimated and was found to take the form of an ellipse envelop in the stress space.