The electrostatic force microscopy (EFM) is used to measure the absolute surface potential on a transmission line model (TLM) structure. The classic electrical measurement taken on the TLM structure has been used to determine the sheet resistance outside the ohmic contact and the contact resistance. Modeling the potential profile along TLM structures has been made using a distributed array of resistances. The sheet resistance of the epitaxial layer under the ohmic contact, (he interfacial resistance and the gold layer resistance are taken into account. The measured potential profile using the EFM technique allows to determine the sheet resistance of the epitaxial layer outside and under the ohmic contact which gives the best fit to the model. These values can be determined with an accuracy better than 5%