The anion substitution of Se by S was found to be an effective way to change continuously the superconducting transition temperature of samples in the Rb-Fe-Se system [1]. Here we present the results of the structural investigation by the single crystal X-ray diffraction analysis of Rb0.8Fe1.6Se2-xSx samples with varying substitution of Se by S in the range 0 ≤ x ≤2. The details of the crystal growth and magnetic characterization are presented in [1]. The structures were determined within the tetragonal space group I4/m which implies two different positions of the tetrahedrally coordinated Fe ions with one general position almost fully occupied (Fe1) and the other at (0.5 0 0.25) almost empty (Fe2). We analyzed the evolution of the lattice parameters, of the bond angles and bond lengths between the ions in function of the substitution concentration. With increasing substitution concentration a nearly linear decrease of both a and c lattice parameters (Fig. 1) was found which can be naturally explained by a smaller ionic radius of the sulfur ion compared to that of the selenium ion. We found a non-monotonic dependence of the occupancy of Fe positions with S doping revealing a minimum (maximum) for the Fe1 (Fe2) sites at x =1.1. We notice that above this substitution magnetic studies revealed the disappearance of the superconductivity [1]. To understand the origin of the continuous variation of the critical temperature for the range 0 ≤x≤1.1 we analyzed the variation of the angles and distances in the Fe tetrahedra. Both Fe1 and Fe2 tetrahedra are found to be irregular. The Se(S)-Fe-Se(S) angles differ significantly from the ideal tetrahedral angle of 109.47º and range from 103.01º to 114.50º. With the increase of the S content the values of the Se(S)-Fe-Se(S) angles increase. The deviation of the Se(S) anions from the Fe planes (anion height) is found to decrease smoothly on increasing of the S concentration. After x> 1.1 the rate of decrease of the anion height considerably changes. We compared our results with the similar data obtained for the related S-substituted KxFe2-ySe2-zSz [2]. It was found that like in the K-derived system the suppression of the superconductivity is accompanied with the increase of the occupation of the Fe2 site, however, in the K system the superconductivity is suppressed at nearly 80% of the substitution, while in our Rb system it disappears already at 55 %.