expenses could vary from quarter to quarter depending on quantity and types of products, as well as the destinations where those goods are being delivered. Further, selling expenses from voxeljet UK significantly decreased as a result of the successful restructuring, which started in the third quarter of 2019. In addition, we incurred lower expenses for travelling, trade fairs and exhibitions related to the COVID-19 situation and the associated global restrictions.
Administrative expenses decreased by kEUR 545, or 7.8% to kEUR 6,407 for the year ended December 31, 2020 from kEUR 6,952 in the prior year period. This was mainly due to significantly lower administrative expense from voxeljet UK as a result of the completed restructuring. In 2019, we faced two exceptional effects, which adversely impacted our administrative expenses. Firstly, we recorded restructuring charges at voxeljet UK and at voxeljet Germany amounting to kEUR 274 and kEUR 45, respectively. Secondly, in 2019 we incurred higher advisor fees mainly related to the previously disclosed Audit Committee Investigation.
Research and development expenses decreased to kEUR 6,500 for the year ended December 31, 2020 from kEUR 7,212 in the same period in 2019, a decrease of kEUR 712, or 9.9%. This was mainly due to lower personnel expenses as a result of the restructuring of the German operation initiated in the first quarter of 2020.
Other operating expenses for the year ended December 31, 2020 were kEUR 2,799 compared to kEUR 945 in the prior year period. This is mainly due to higher losses from foreign currency translations. Foreign currency losses amounted to kEUR 2,545 for the year ended December 31, 2020, compared to kEUR 880 in the same period in 2019.
Other operating income was kEUR 1,603 for the year ended December 31, 2020 compared to kEUR 2,143 in the prior year period. The decrease was mainly due to lower gains from foreign currency transactions of kEUR 849 in 2020 compared to kEUR 1,657 in 2019. This was partially offset by a government grant received by voxeljet America in April 2020 from the United States Small Business Administration (“SBA”) under the COVID-19 funding program amounting to kEUR 295. The full amount was recognized in profit and loss, in the second quarter of 2020, as the related costs for which the grant is intended to compensate occurred in this period and we assume that we comply with the conditions of the funding. The assessment of SBA whether we are in compliance with the conditions has not been performed yet.
The changes in foreign currency losses and gains were primarily driven by the valuation of the intercompany loans granted by the parent company to our UK and US subsidiaries.
Operating loss was kEUR 13,164 for the year ended December 31, 2020, compared to an operating loss of kEUR 12,908 in the comparative period in 2019. This was mainly due to a negative net impact of the year over year changes in other operating expenses and other operating income amounting to kEUR 2,394. In addition, gross profit for 2020 decreased by kEUR 421 compared to last year. This was almost fully offset by significant cost savings within each of our functions. Year over year, selling expenses, research and development expenses and administrative expenses declined by kEUR 1,302, kEUR 712 and kEUR 545, respectively.
Financial result was negative kEUR 2,405 for the year ended December 31, 2020, compared to negative kEUR 1,031 in the comparative period in 2019. This was mainly due to higher interest expense for long-term debt which amounted to kEUR 1,602 in 2020, compared to kEUR 993 in 2019. This was mainly related to the fixed interest related to the first portion of the second tranche (tranche B1) of the loan granted by the EIB amounting to kEUR 5,000, which has been drawn down in June 2020. In addition, the impact from the revaluation of derivative financial instruments amounted to negative kEUR 807 for 2020, compared to negative kEUR 106 in 2019, which leads to a year over year change of negative kEUR 701.
Net loss for the year ended December 31, 2020 was kEUR 15,481, or EUR 3.20 per share, as compared to net loss of kEUR 13,978, or EUR 2.89 per share in the prior year period.
Effective August 14, 2020, we changed the ratio of our ADSs to ordinary shares from each ADS representing one-fifth (1/5) of one ordinary share (5:1) to each ADS representing one ordinary share (1:1). Based on a conversion rate of one ADSs per ordinary share, net loss was EUR 3.20 per ADS for the year ended December 31, 2020, compared to net loss of EUR 0.58 per ADS in the prior year period, based on a conversion rate of five ADSs per ordinary share.