An environmentally friendly, economically beneficial and appropriate for Latvia gray alder (GA) wood processing technology was developed to produce high-quality granular activated carbon (GAC), using previously known and improved hydrothermal and thermochemical wood-processing techniques. The main feature of the technology is improvement of GA wood by hydrothermal pretreatment in a steam media at elevated temperature under pressure with subsequent pelletization in a flat die pelletizator; thereby the competitiveness of the GA wood in the overall market increases. Taking into account both environmental and energy aspects, appropriate hydrothermal treatment equipment was chosen. As well as optimal hydrothermal pretreatment parameters were developed and fractional composition of the raw material was selected to obtain modified wood (MW) with high enough content of water-soluble substances (10%), which acts as a binder in the pelletization process. Optimized pelletization process (moisture content, fractional composition and the content of hot water - soluble substances) ensure that the resulting pellets are suitable for obtaining high-quality GAC. Using thermogravimetric analysis, the thermal stability of the raw GA and MW was examined depending on the hydrothermal treatment time. It is shown that by increasing the duration of hydrothermal pretreatment the thermal stability of the obtained MW pellets also increases due to the higher lignin and cellulose content, wherewith the activated carbon yield is higher. Optimal parameters of the carbonization and activation process were developed to obtain dense (bulk density 457 g/l) GAC with high yield (20.9%), low abrasion (4.3%) and low ash content (4.5%). Obtained GAC has a well developed pores structure (BET surface area 1069.6 m2/g, total pore volume 780.9 mm3/g, micropore volume 304.1 mm3/g) and has a high adsorption capacity (iodine 973mg/g, methylene blue 88 mg/g, methylviolet 41 mg/g). GAC properties are similar to those GAO obtained from coconut shells. The doctoral thesis is written in Latvian, it consists of 121 pages, 27 images, 28 tables, 12 equations and 2 attachments; 132 references were used in the work.