A new method for quickly determining low EOF rates 4(mu(EOF)) in microchip CE is described. The measurement is based on the notion that the effective mobility (mu(eff)) of an analyte is a constant in a certain BGE. The mu(eff) of an analyte is determined in a reference fast-electroosmosis microchip, and the apparent mobility (mu(app)) of the analyte can be determined in the microchip with unknown low electroosmosis, and then mu(EOF) in the low-electroosmosis microchip can be calculated according to the equation mu(EOF) =mu(app)-mu(eff). By an indirect method or other conventional methods, mu(eff) can be easily measured in the reference microchip. The proposed method is particularly useful for low-electroosmosis measurements in wall-modified microchannels.