A protocol for the transformation of Klebsiella oxytoca by electroporation was developed. Preparation of competent cells at early exponential phase was most critical to obtain a high transformation efficiency. The highest efficiency of 1.6 × 10 transformants per μg DNA (pBR 322) could be obtained by electroporation of K. oxytoca cells prepared at the OD600 of 0.2 with 1.25 μg DNA at the filed strength of 2.5 kV, the parallel resistance of 200 Ω and capacitance of 25μF.