The electrical conductivity measurements on single crystals and powdered pellets of KH2PO4 have been carried out in the temperature range from 80 to 230 degrees C with various heating rates. No experimental evidences of the high-temperature phase transition were found, and the conductivity data could be interpreted solely as the chemical decomposition which occurs near 190 degrees C. Raman studies were made to analyze the constitution of the dehydrated KH2PO4