3 & 4-(nitrooxymethyl)benzoyl chloride were obtained from the corresponding chloromethyl derivatives. Further reaction with TMSP was investigated with the purpose of obtaining the hydroxy(3- and 4-(nitrooxymethyl)phenyl)bisphosphonic acid, a potentially useful agent against osteoporosis. Bisphosphonates (BP) are known for their exceptional affinity for bone tissue and as an inhibitor of bone resorption. Nitrooxy-donor groups were found to affect osteoclastic activity by inhibiting the differentiation of preosteoclastic cells to functional osteoclastic cells. The attachment of a nitrooxy-donor function to BP will increase the utility of these molecules as therapeutic agents against bone disease.