The positron lifetime spectroscopy and the Doppler broadening of annihilation radiation lineshape (DBARL) techniques have been used in conjunction to study temperature effects on positronium (Ps) inhibition in water. As found in the previous works of this series, NO 3 − leads to complete inhibition with increasing concentration; in contrast, Cl − and Tl − suppress only a fraction of Ps, which is the same for the two solutes. The results from DBARL show that NO 3 − and Tl + inhibit Ps formation by electron scavenging, while Cl − captures the positron to form a bound state. The slight decrease of the inhibiting power of NO 3 − with temperature T again points to this ion capturing quasi-free electrons, in competition with the solvation process. On the other hand, the strong dependence of the Tl + inhibition constant on T indicates that this ion operates by reacting with electrons associated with the fluid, although probably not fully solvated. The anomalous behaviour of the (Cl −e +) bound state intensity with Cl − concentration and the small effect of T on the Cl − inhibition constant, in marked contrast to what is observed in other polar solvents, betray the implication of some additional process in the inhibition. Trial experiments show however that the formation of Cl 2 − is not likely to be invoked.