The reactions of Ti+ with methylphosphine in the gas phase have been characterized using the technique of Fourier transform mass spectrometry. Elimination of H-2 is the initial reaction of the metal ion with CH3PH2. Using CH3PD2 as the substrate resulted in a loss of D-2, which supports the initial formation of [Ti=PMe](+). Collision-induced dissociation (CID) and ion-molecule reactions, however, give evidence for a rapid conversion to the presumably more stable [TiP(H)=CH2](+). The product from the primary reaction reacts further in successive steps with the neutral methylphosphine to form a variety of higher order ionic reaction products, including the series TiP2+ --> TiHP3+ --> TiP4+ --> TiHP5+ --> TiP6+. CID and general bonding principles are not inconsistent with the formation of titanium phosphacycles, in particular TiP4+ with a five-membered ring structure, but other possible structures are also discussed.