The contact charging of two planetary analog dust samples are investigated in a simple experiment. Dust particles of lunar (JSC‐1) and Martian (JSC‐MARS‐1) regolith simulants are brought into contact with metals of known work function (Co, Ni, Au, Pt) and the resulting contact charge is measured. The dust charge is typically 105 elementary charges for a ∼100 micron dust particle and increases with repeated agitation of the surface. The dust charge scales linearly the work function of the contacting surface. The effective work functions of the planetary analogs are determined by extrapolation to be 5.8 eV and 5.6 eV for the lunar and Martian dust simulants, respectively. Additional measurements are made with oxidized metal surfaces and a glass surface.