The effect of supersaturation and temperature on the particle morphology of L-Glutamic acid and an aromatic amine derivative has been compared by pH-shift precipitation in water at temperatures of 5-80 °C. Both systems show switching from single crystals to polycrystalline particles as the initial supersaturation is increased. The polycrystalline particles have been identified to grow by a spherulitic growth mechanism. The aromatic amine derivative shows switching from monocrystalline plate-like crystals at a constant supersaturation value, whereas L-Glutamic acid displays a transition from needles to spherulites, at a supersaturation level that becomes lower as the temperature increases. The spherulite morphology changes with supersaturation, becoming more compact at higher supersaturation ratios.