This dataset contains Physical and Chemical Properties from Selected Expeditions in the Arctic Ocean. This data collection includes measurements of temperature, salinity, conductivity, pH, and concentrations of silicate, oxygen, nitrate, nitrite, and phosphorus in the Arctic Ocean. The data were collected sporadically since 1950, from icebreakers, research vessels, and ice camps using traditional wire casts, CTD (conductivity, temperature, depth) casts, and CTD/rosette casts. Also included are positional data and, for some expeditions, derived measurements of oxygen, nutrients, and alkalinity. The data are in NODC .SD2 and .F022 formats. The purpose of this data collection is to preserve and distribute physical and chemical data from the Arctic Ocean that have been gathered through a cooperative international effort involving the United States, Canada, Germany, Sweden, and Russia.