SANS data from solutions of sulfite reductase dodecamer in 50 mM KPi, 100 mM NaCl, 1 mM EDTA, pH 7.8 were collected using the EQ-SANS (BL-6) spallation neutron source (Oak Ridge, Tennessee, USA). This sample is a dodecameric oligomer containing a His-tagged SiRFP octamer and four copies of SiRHP. Three instrument configurations were used: 9 m sample-to-detector distance with 1.5 nm wavelength band, 4 m sample-to-detector distance with 0.6 nm wavelength band, and 1.3 m sample-to-detector distance with a 0.4 nm wavelength band. Sample concentration: 3 mg/mL. Neutron exposure time: 3 hours / instrument configuration. Sample temperature, 8°C.