The mathematical Lambert function W[a exp(a - bt)] is used to find integrated rate laws for several examples, including simple enzyme and Lindemann-Christiansen-Hinshelwood (LCH) unimolecular decay kinetics. The results derived here for the well-known LCH mechanism as well as for a dimer-monomer reaction mechanism appear to be novel. A nonlinear fit of published enzyme kinetics data to a function of this type using Mathematica 7.0 is also shown. The prevalence of simple enzyme and LCH models in teaching and research makes the derivation of integrated rate laws for these cases of particular interest. (Contains 2 figures.)