For the study of the micro-regional properties of soils,microelectrodes are useful for the measurements of redox potential,pH value and electric conductance.When the buffered solutions were saturated with quinhydrone,the values of theoretical potentials can be obtained by the micro pt electrode with a diameter of 0.5 mm and length of 0.2 mm.If redox potentials of soils are ranged from 80 to 450 mv,2-5 my lower than the ordinary large electrode were found as measured by the microelectrode.For the measurement of pH value of air-dried soils,the difference between the micro quinhydrone electrode and the glass electrode was insignificant.In water-logged soils with a redox potential below 350 mv,however,the exverimental error may be 0.3-0.6 pH unit.