In order to investigate the processes leading to the chemical loss of ozone in the Arctic, EASOE (European Arctic Stratospheric Ozone Experiment) took place from November 1991 to March 1992. During this campaign we made four balloon-borne measurements at Esrange (68°N, 20°E) near Kiruna, Sweden in December 1991 and January 1992. Scientists from Nagoya University made measurements of total reactive nitrogen (NO_y), nitric oxide (NO), ozone, and aerosols. On the same gondola, instruments to measure nitric acid (HNO_3), O_3,N_2O, CFC_s, and the photodissociation coefficient of NO_2 from University of Denver, CNRS of France, and KFA of Germany were also mounted. The results on the concentrations of NO_y, NO, O_3,N_2O, and aerosols obtained on January 22 and 31 are reported.