In the Doctoral Thesis for the first time the impact of technological parameters of the expanded polystyrene block manufacturing process and set of block quality ensuring factors were systematically researched for openly published. The product’s properties in blocks were investigated, referring to EN defined norms and analysis methods, as well as using light microscopy and granulometry methods. In the course of work, the influence of raw material granulometry and influence of technological parameters of block manufacturing process on the product’s properties in EPS blocks volume (compression stress, tensile strength, density, heat conductivity, water absorption) were determined. Recommendations for the EPS block quality improvement were formulated. In the literature review the information on the expanded polystyrene product properties, structure and influencing values of the preparation parameters has been summarized and evaluated for the period from 1981 to 2010. The Doctoral Thesis has been written in the Latvian language, its volume is 127 pages. The Thesis consists of 99 pictures, 15 tables and 86 literature sources have been used in it.