The issue covers selected papers presented during MicroTherm 2019 – International Conference on Microtechnology and Thermal Problems in Electronics. The conference was held on 24-26 June 2019 in Lodz, academic, post-industrial city located in the centre of Poland. MicroTherm is a cyclic event. This edition gathered about 80 participants from 8 countries.MicroTherm is an International Conference, which has been organised every two years, since 1996, by the enthusiastic scientific team from Lodz University of Technology supported by the academic group from Warsaw University of Technology. The success of the first seminar, devoted to thermal management in electronics, and the successive conferences has led us to the thirteenth edition. Since the first meeting, the scope of the Conference has expanded, following the progress in micro and nanoelectronics. Currently, it covers the subjects concerning extreme temperature electronics, sensors and measurement techniques, modelling, simulation, wide band-gap materials and nanomaterials, packaging and reliability, renewable energy sources and photonics with particular emphasis on micro- and nanotechnologies. Traditionally, the programme of MicroTherm, included invited talks, regular sessions in forms of both planar discussions and poster presentations, and also special Students’ Session. The latter gave an opportunity for students and young researchers to present their first achievements in the field of science.On behalf of Organising and Scientific Committees, we would like to thank all the Participants of MicroTherm 2019 Conference for their contribution in this scientific event. We would like also to express our gratitude to the Ministry of Science and Higher Education of Poland for the financial support of the conference. More information about MicroTherm 2019 and details about the forthcoming event are available at the conference website soon (http://www.micro.semtherm.eu).