X-ray diffraction measurement for a single crystal of NaxCrxTi8-xO16 (x approximate to 1.7) has been performed at 773 K. The structure is characterized by a host framework containing one-dimensional tunnels extending along the c axis, The tunnel is described as an infinite chain of pseudocuboetahedral cavities where Na+ ions are located. The Na sites in a cavity deviate from the cavity center in directions normal to or along the tunnel axis. A bottleneck, i.e. a boundary of adjacent cavities, is also used as a Na position. These results are basically the same as those obtained at room temperature. An electron density map at section x = 0 obtained from the maximum entropy method was naturally more broad at 773 K than at room temperature. The Na+ ion suffers almost no bottlenecking effect, even at 773 K, judging from the electron density distribution along the tunnel.