Abstract A Landau-Ginzburg model is proposed as a phenomenological description of both standard and high temperature superconductors. Attention is drawn to a direct link with a microscopic second-quantized Hamiltonian. Exact solutions of the equations of state are found and discussed both in the absence and presence of superconducting currents. Qualitative agreement is found for the critical current as a function of the reduced temperature. The importance of the short coherence length in high T c superconductors and the correlation between this and the sign of the effective mass is pointed out.