A symbolic computer language SMP* is employed to analytically solve sets of first-order linear differential equations which occur in kinetic rate-reaction studies. The solutions studied are fully analytic functions of time and the rate constants. Two typical systems are studied the first contains four species and four rate constants, corresponding to four parallel and consecutive first-order reactions; and the second contains four species and six rate constants, including two additional reverse reactions. These analytic functions allow insight into the mechanism, analytic expressions for the rate constants, and more rapid and precise solutions for the species concentrations than a completely numerical solution of the differential rate equations themselves. The results of the first system are applied to a recent experimental study of enzyme kinetics in which constituent amino acid residues of an enzyme are photooxidized and the corresponding catalytic activity measured with time. A second application of the SMP gives rise to a rapid semianalytic method for obtaining the values of the four and six exponentially nonlinear rate constants from the experimental data.