This International Standard specifies a method for the determination of the electrical rest conductivity of aviation and distillate fuels with or without a static dissipator additive. The method measures conductivity when the fuel is uncharged, i.e. electrically at rest (known as rest conductivity). Two methods are available for fuel conductivity measurement, either using a portable meter for the direct measurement in tanks or laboratory and field measurement of samples, or using an in-line meter for continuous measurement of fuel conductivities (equivalent to rest conductivity) in a flowing stream. When using either type of instrument care should be taken in allowing the relaxation of residual electrical charges before measurement and in preventing contamination. The procedure can be used to measure conductivities from 1 pS/m to 2 000 pS/m using the equipment used to establish the reported precision. The range can be extended to greater than 2 000 pS/m with the correct selection of electrode size and current measuring apparatus.