The role of NPs as theranostic agents in the treatment and diagnosis of diseases is becoming increasingly important. The development and characterization of new nanoparticulate systems is crucial for the discovery of new potential therapies and imaging strategies. We have developed in our laboratory fluorinated core-shell gold nanoparticles that can simultaneously work as 19F MRI agents and drug delivery systems. Small angle neutron scattering (SANS) is a widely used technique for investigating nano-scaled systems as it allows a detailed structural characterization at the nanoscale. Here we propose a SANS study to determine the structure of different core-shell theranostic gold NPs.