The interaction between the main protein components of rapeseed, also called canola, was investigated in water as a function of the pH and in the presence of NaCl. Firstly, the solubility of purified cruciferin and napin was determined and the soluble fraction was characterized using light scattering techniques. Napin was found to be soluble over the whole pH range investigated (pH 4–10), whereas cruciferin was only partially soluble at pH ≤ 7. Subsequently, mixtures of the two components were studied as a function of the pH showing that large complexes between the positively charged napin and the negatively charged cruciferin were formed at pH ≥ 7 in water that could be removed by filtration through 0.2 μm pore size filters. It was found that the extent of complexation strongly depended on the fraction of napin in the mixture. Interestingly, in the presence of 0.1 M NaCl much smaller complexes were formed in this pH range that remained in solution.