Electrical properties of thin iron films deposited at room temperature both on clean Si(100) and prefabricated surface phase Si(100)-c(4×12)-Al were studied by means of in situ Hall effect registration and conductance measurements. It was shown that Si(100)-c(4×12)-Al surface phase blocks intermixing of iron and substrate atoms. Conductance and mobility of the majority carriers in this surface phase is higher than that in Si(100)2×1 within the temperature range from room temperature to 180°C. Deposition of less than 25 monolayers of iron on the clean Si(100) resulted in significant reduction of conductance. Continuous iron film on Si(100)-c(4×12)-Al forms at coverage approximately twice thinner compared to deposition on Si(100)2×1. [DOI: 10.1380/ejssnt.2009.167]