We provide a validated and rapid protocol for the solubilization of amyloid β-peptide (Aβ). This procedure involves sequential solubilization using structure-breaking organic solvents hexafluoroisopropanol and DMSO followed by column purification. The low solubility and tendency of Aβ to aggregate considerably impede the in vitro handling and biophysical or biological investigation of Aβ, despite the interest in this peptide because of its implication in Alzheimer's disease. The main advantage of the proposed protocol over others is that it results in standardized aggregate-free Aβ peptide samples that are biocompatible for cell culture studies and yield reproducible aggregation kinetics and cytotoxicities. This three-step protocol also enables the co-solubilization of the longer Aβ42 variant with Aβ40 in ratios relevant to Alzheimer's disease.