Previous IR studies of nitrocellulose and attempts to determine nitrocellulose and the N content of nitrocellulose by IR are reviewed. An IR method for the determination of N in nitrocellulose is proposed whereby the sample is dissolved in tetrahydrofuran by standing overnight and the transmittance of the band at 6 microns measured. Various factors affecting the method were considered. The results for the proposed method compare well with the results obtained by the nitrometer method. The precision of the method is about !0.09%.