Summary: We solve the unification problem for linear temporal logic (\(\mathcal {LTL}\)). For any given formula \(\varphi \), we verify if \(\varphi \) is unifiable in \(\mathcal {LTL}\); if yes, we construct its unfolded form; and, next, by this form we directly write out the most general unifier for \(\varphi \). Thus, we show any formula unifiable in \(\mathcal {LTL}\) has a most general unifier (thus, \(\mathcal {LTL}\) enjoys unitary unification), though we also show that there are formulas unifiable in \(\mathcal {LTL}\) which are not projective.