The ligand exchange mechanism of solvated lithium cations has been studied using DFT calculations (RB3LYP/6-311+G**). The water exchange mechanism on [Li(H2O)(4)](+) was found to be limiting associative (A) involving a five-coordinate intermediate, whereas ammonia exchange on [Li(NH3)(4)](+) was found to follow an associative interchange (I-a) mechanism. The suggested mechanisms are discussed in reference to available experimental and theoretical data.