The doctoral thesis “The effect of mullite-forming additives on the properties of porous alumina ceramics” researches the impact of mullite-forming additives of different chemical compositions and dispersity rates on the ceramic, mechanical, and thermal properties of highly porous (apparent porosity >50%) Al2O3 ceramics. The doctoral thesis consists of an introduction, three main chapters (Literature Review, Materials and Methods, Experimental Results and Discussion), conclusions, a list of sources used, and appendices. The literature review, covering a period from 1924 till 2015, summarises information on the main uses and fabrication methods of porous ceramics, the widely used Al2O3 composite materials, and the possibilities for improvement of the mechanical and thermal properties of Al2O3 ceramics. The second chapter describes the materials and methods used to achieve the aims of the doctoral thesis. The experimental part studies the effect of mullite-forming additives (micro-sized SiO2 and SiC and SiC, Si3N4, Si3N4 Al2O3 Y2O3 nanopowders) on the bulk density, apparent porosity, mechanical strength, thermal shock resistance and thermal conductivity (including its dependence on the temperature) of porous Al2O3 ceramics. The relation between the microstructure of the materials and the properties mentioned above is also explained. The doctoral thesis is written in Latvian and is 149 pages in length. The thesis contains 59 figures, 9 tables, 27 equations, and 5 appendices, and there are 245 sources of reference used.