Laminar diffusion jet flames are subjected to buoyant instabilities when the Froude number is lower than a critical value. In the present work, a numerical study on syngas laminar jet diffusion flames at elevated pressures (1, 2, 4, 8 and 12 bar) and buoyant instabilities is presented. Since the Reynolds number is kept constant, the velocity and Froude number diminish as pressure is increased. For pressures from 1 to 4 bar the flames display a steady behavior with a progressive reduction of the thickness, while for 8 and 12 bar the flames oscillate and pulsate. These predictions are consistent with experimental observations. Furthermore, for the unsteady flames, the pulsation of the flame thickness and spatial oscillations are quantified and analyzed
