The Pu4+, Np4+, and U4+ ions, which have large electron affinities of similar to 34.6, similar to 33.6, and similar to 32.6 eV, respectively, were stabilized from solution to the gas phase upon coordination by three neutral tetramethyl-3-oxa-glutaramide ligands (TMOGA). Both collision induced dissociation (CID) and electron transfer dissociation (ETD) of Pu(TMOGA)(3)(4+) reveal the propensity for reduction of Pu(IV) to Pu(III), by loss of TMOGA(+) in CID and by simple electron transfer in ETD. The reduction of Pu(IV) is in distinct contrast to retention of Th(IV) in both CID and ETD of Th(TMOGA)(3)(4+), where only the C-O-ether bond cleavage product was observed. U(TMOGA)(3)(4+) behaves similarly to Th(TMOGA)(3)(4+) upon CID and ETD, while the fragmentation patterns of Np(TMOGA)(3)(4+) lie between those of Pu(TMOGA)(3)(4+). and U(TMOGA)(3)(4+). It is notable that the gas-phase fragmentation behaviors of these exceptional tetrapositive complexes parallel fundamental differences in condensed phase chemistry within the actinide series, specifically the tendency for reduction from the IV to III oxidation states.