We report the development of an improved bacterial expression system for the amyotrophic lateral sclerosis (ALS)-associated protein superoxide dismutase 1 (SOD1). The unmodified coding sequence for wild-type human SOD1 (WT SOD1) was cloned into a pET vector to ease expression and export into the periplasmic space of Escherichia coli. Export into the periplasm leads to cleavage of a vector-derived pelB signal sequence, releasing the soluble full-length protein without a tag into the periplasmic space. WT SOD1 was purified from the periplasmic space by osmotic shock, differential heat precipitation, ammonium sulfate precipitation, and a single hydrophobic interaction chromatography step. The strategy used to express and purify WT SOD1 was also applied to mutant versions of the protein, A4V and G93A SOD1, thus providing a generic method for purifying not only WT SOD1 but also disease associated mutant SOD1 variants. The aggregates formed by the three SOD1 proteins as measured by the Thioflavin T assay followed the nucleation-dependent polymerization kinetics reported for SOD1. All three SOD1 proteins produced amorphous aggregates as shown by electron microscopy that were toxic to Neuro2a cells. The method presented here can be used as a generic rapid and inexpensive method for producing wild-type and mutant SOD1 proteins without having to use peptide tags and enzymatic cleavage for protein purification.