It was shown that dihydrodiphenylsilane appeared to be an efficient promoter for the hexene-1 metathesis reaction conducted in the ionic liquid 1-buthyl-3-methylimidazolium tetrafluoroborate that contained WCl6 and WOCl4 as catalysts. However, dihydrodiphenylsilane had no promoting effect in the 1-butyl-3-methylimidazolium hexafluorophosphate + WCl6 system. The promoting activity of the organometal compound was found to substantially drop in the order dihydrodiphenylsilane, dihydrodiphenylgermane, diphenyidichlorosilane.