The paper deals with relevant methodological and practical aspects of automatic cross-border transmission capacity assessment in electric power interconnections. It is based on advanced methodology for steady-state security analyses, using all its favourable properties, respecting the latest criterions, standards and practice of European Transmission System Operators (ETSO). The practical presentation of developed computer program is made on example of transmission capacity calculation in condition of ex Second UCTE synchronous zone. This presentation gives an overview of the characteristics and possibilities of this computer program, regarding the real necessities of operational practice in new conditions of liberalized electricity markets. .