This paper describes the design and construction of compact iron‐free solenoid magnets cooled by immersion in liquid nitrogen. Construction details and performance data are given for two such magnets, which produce a magnetic field of 4000 gauss with a power expenditure of 2.7 to 3.3 kw. Heat transfer coefficients between copper wire and boiling liquid nitrogen have been measured for temperature differences between the wire and the liquid of 2 to 11°K.