A cationic Rh(I)/1,1'-bis(diphenylphosphino)ferrocene (dppf) complex catalyzes isomerization of allyl propargyl ethers to allenic aldehydes in good yields at room temp. 40ツー. At 80ツー, carbonyl migration from allenic aldehydes proceeds further to give dienals in good yields. The cationic Rh(I)/dppf complex acts as a dual catalyst for activation of マ? and マ?bonds in these isomerization reactions. [on SciFinder(R)]