2-Methylpropane and 2-methylpropene, in the presence of the W(H)(3)/Al(2)O(3) catalyst, are unexpectedly transformed to 2,3-dimethylbutane and 2,3-dimethylbutenes, respectively, with high selectivity; in case of 2-methylpropane, this reaction represents the first example of the transfer of two carbons in alkane metathesis.