The effects of cold work and phosphorous on ductile to brittle transition behavior were investigated in order to evaluate the effects of hardening and intergranular degradation on the ductile to brittle transition temperature (DBTT) of F82H steel. Yield strength and ultimate tensile strength are increased by increasing the level of cold work. Phosphorous additions resulted in a small increase in the strength of F82H. The DBTT after cold work is shifted to high temperature and upper shelf energy (USE) is decreased. The shift of DBTT and the reduction of USE increase with the cold work level. F82H as-received and cold worked steel fractured in a cleavage mode at temperatures of lower shelf energy (LSE) region. The DBTT is shifted to higher temperatures with increasing phosphorus additions accompanied by the reduction of the USE. Although the hardening is small, a significant embrittlement was observed in the steels added with phosphorus, which was accompanied by intergranular cracking at temperatures in LSE region.