Ruthenium olefin metathesis catalysts were evaluated for the ethenolysis of trans-5-decene, a model compound of internal olefins, to produce alpha-olefin. N-heterocyclic carbene (NHC) ruthenium metathesis catalysts were found generally better than sole phosphine based ruthenium analogs toward the ethenolysis of internal olefin in terms of conversion and selectivity. Especially, dichloro[1,3-bis(2,6-isopropylphenyl)-2-imidazolidinylidene](2-isopropoxyphenylmethylene)ruthenium(II) (HG-C711) demonstrated excellent activity and selectivity for the formation of terminal olefins even at relatively low catalyst loading. A catalyst comparison showed that ruthenium catalysts bearing sterically hindered NHC substituents afforded greater selectivity and stability. However, reactivity loss due to catalyst decomposition limited the catalyst turnover numbers well below commercial viability. Those preliminary studies shed some light on the synthesis of alpha-olefins by ruthenium catalyzed ethenolysis, which will be fundamental knowledge for future understanding of factors influencing catalyst performance and help further development of this particular interesting methodology to achieve a commercially economically viable process.