This research is directed toward providing physical data that is useful for fast neutron radiotherapy. The data that will be provided are the measured kerma factors for various materials of biological interest. The kerma factors will be measured using specially constructed calorimetric dosimeters. These measurements have high accuracy and can be used as bench marks against which calculations and measurements by other techniques, can be compared. In addition, the calorimetric technique is being developed and improved. Such improvements will make the technique more accessible and useful for other clinical researchers. Developments of calorimetric dosimetry should have broad applications in the clinical dosimetry for radiation therapy.