Thermal lance is one of the methods for concrete cutting/piercing. The burning lance not only provides high temperature to melt the concrete target in the form of lava, but also has a eutectic effect changing the lava melting temperature. The eutectic effects by adding lance material such as FeO, Al2O3 and TiO2 to concrete (SiO2-CaO) system are discussed. The discussion and concrete piercing experiments both show that, due to eutectic generation effects, aluminum and titanium modified lances are not effective on concrete objects although these lances provide high lance temperature. Iron based lance is the most effective thermal lance due to its eutectic generation effect. Experimental results of cutting improvement by using chemically modified iron lance are presented and the eutectic generation effect in this process is discussed. (C) 2004 Kluwer Academic Publishers.