Several preparation techniques for the preparation of mortar samples for corrosion rate measurements of steel in chloride contaminated concrete are presented and the accompanying errors described. It was not possible to achieve a mortar sample preparation with a steel electrode including electrical connection embedded completely in the mortar. The most significant errors came from crevice corrosion under the sealants and coatings applied for limiting the exposed steel surface and for electrical insulation. The only successful preparation technique was that described by Andrade in 1980 in which an insulation tape was wrapped around the steel rods at the exposed ends pushed into the mortar, the steel outside the mortar being covered with Vaseline to prevent atmospheric corrosion.