The aim of our investigation was to compare several technologies for obtaining granular activated carbon from wood of a fast growing deciduous tree species, grey alder (Alnus incana (L.) Moench). High-quality granular carbons are characterized by high density and mechanical strength, and a high sorption capacity from the gas-vapour medium. A technology for obtaining this sorbent from deciduous wood is being developed at the Latvian State Institute of Wood Chemistry. The basic processes of the technology are chipping, milling, hydrothermal modification of wood, drying (if necessary), pelletizing, carbonization and activation with superheated steam. When developing the technology, the minimum energy consumption, the minimum quantity of emissions and their pollution degree are taken into account among the parameters of the optimum solution. The tested hydrothermal treatment versions are as follows: 1) treatment of water-saturated wood in a laboratory scale autoclave; 2) treatment of wood in an autoclave with batch supply of saturated steam and blow-off; 3) treatment of wood in a steam flow reactor; 4) treatment of dry wood in a pilot scale batch autoclave.