Two oleogum resin essential oils (from two different seasons: fall and summer), of Boswellia spp. (collected from Somalia), were obtained by hydrodistillation and analyzed by GC-MS. Out of 147 peaks, components were identified among the two essential oils accounting for 100%, and 99.7% of the oils, respectively. The two essential oils were dominated by the 1-methoxy alkane [octyl methyl ether (5.5- 11.7%), and decyl methyl ether (30.6-54.9%)], Î±-pinene (0.3-11.5%), sabinene (2.1-7.2%), and Î±- bourbonene(1.7-5.7%). This is the first report of a methoxy alkane chemotyped frankincense essential oils as well as the first reporting of the natural occurance of decyl methyl ether (methyoxy decane) and octyl methyl ether (methyoxy octane). Monoterpenes chiral distributions were also measured and it was found that both of the oils have same enantiomeric ratio. Large chemical variation was attributed to seasonal variation. The essential oil harvested on fall season had also exhibited notable antimicrobial activities [Aspergillus niger (MIC = 39 Î¼g/mL), Candida albicans (MIC = 78 Î¼g/mL), Bacillus cerreus (MIC = 78 Î¼g/mL), Staphylococus aureus (MIC = 78 Î¼g/mL), and Escherichia coli (MIC = 78 Î¼g/mL)], the essential oil also showed pronounced cytotoxic activities (100% kill on MCF-7 cells at 100 Î¼g/mL).