Various implementations directed to determining three-dimensional (3D) rock properties using cross well seismic are provided. In one implementation, a method may include receiving 3D seismic data acquired in a seismic survey of a region of interest. The method may also include receiving cross well seismic data acquired in a cross well seismic survey of the region of interest. The method may further include determining a first set of rock properties of the region of interest based on the cross well seismic data. The method may additionally include determining one or more variograms based on the first set of rock properties. The method may also include determining one or more 3D rock properties of the region of interest based on the one or more variograms and the 3D seismic data.