The force acting on the tip during its immersion in the double layer region was measured for various tip-approaching velocities. The double layer electric field acting on the tip results in a repulsive force component when the tip is immersed in the diffuse layer corresponding to a region far away from the liquid/solid interface (similar to 100 nm) and an attraction when it is immersed in the near-surface layer (similar to 2 nm). For higher values than 10 mu m/s (in water), the transient force on the tip results from the interaction of two double layers (Si3N4 tip and mica substrate) with their charge distribution in a nonequilibrium situation. In the inner layer, the thickness of the interaction region as well as the force on the tip decrease with an increasing approaching speed while in the diffuse layer there is a force increase with an approaching velocity. Dimethyl sulfoxide shows only a repulsive force, indicating that the attraction in the near-surface layer in water is associated with a variable water dielectric constant at the liquid/solid interface. In water the measured transient forces as a function of the tip/substrate distance show a relaxation time of similar to 1.1 ms when the tip is immersed in the inner layer while the diffuse layer shows a relaxation time of similar to 5.6 ms. The measured diffuse layer relaxation time for dimethyl sulfoxide is similar to 0.5 ms.