Here we describe a new instrument for surface stress measurements in monolayers of self-assembled films–thiol molecules on a cantilever surface. The device is constructed on the basis of an atomic force microscope. Our main interest was the relation between electrostatic forces and hydrogen bonds forces acting in the thiol monolayers. It was shown that sorption of the thiol monomers onto the cantilever surface causes its deflection. In the case when thiols with amino groups were used the cantilever bent towards the golden side of the cantilever, which has been covered by thiols. The monomers, which did not have amino groups, caused the bent in the opposite direction.