The wingspan of the common brimstone butterfly measures between 52 and 60 millimetres. The male brimstone is bright yellow, while the female has a greenish tinge. Both have an orange spot at the centre of each wing and a unique angular wing shape. The larvae are green, but the surface of the body is densely covered with tiny black projections tipped with white.
The common brimstone lives in forest clearings and along the banks of rivers and streams. The butterflies are on the wing between July and October and from March to May. They hibernate as adults.
The butterflies feed on flowers, and the larvae feed on buckthorn.