The dual-phase-lag ( DPL ) heat conduction model was used to study transient free convection flow in vertical plates with isoflux and adiabatic thermal boundary conditions at one insulated wall. The DPL model expression was used to formulate the energy equation. The time-dependent governing equations are solved via the Laplace transform technique. Semi-analytical solutions for temperature, velocity, and skin friction are obtained through the inversion of solutions in the Laplace domain to the time domain by a numerical procedure called Riemann sum approximation. The effects of significant parameters on temperature and velocity are graphically and in tabular form. Also, the skin friction is presented in tabular form with the aid of the MATLAB program. It is imperative to give remark that, temperature decreases and increases before and after a critical ( C r ) point as thermal retardation time and Prandtl number increase with time. However, the converse was the case when τ q and Pr number increased at a fixed time. Also, velocity increases at a low Prandtl number and increases at a high Prandtl number as thermal retardation time increases. Conversely, the reverse was the case on velocity due to increased thermal relaxation time.