3-[1-[4-(2-Methylpropyephenyl] ethyl]-6-(4-fluorophenyl)-1,2,4-triazolo [3,4-b] -1,3,4-thiadiazole (C21H21FN4S) has been synthesized as a member of a series of triazolothiadiazoles having NSAIDs moieties with cytotoxic activity. The crystal structure of this new compound has been solved and refined using conventional laboratory X-ray powder diffraction data and optimized using density functional techniques. The final structure solution was achieved by Rietveld refinement using soft restraints on all non-H atom bond lengths and angles. This compound crystallizes in P (1) over bar space group, with the unit cell parameters a= 5.5880(4) angstrom, b = 9.3074(7) angstrom, c = 19.497(4) angstrom, alpha= 99.311 (10)degrees, beta= 91.925(9)degrees, gamma= 98.199(6)degrees, and V= 988.8(2) angstrom(3). To complement and verify the structure solution of the compound, the density functional theory (DFT) calculations were performed by using the local density approximation and the generalized gradient approximation for exchange-correlation energy. In order to see the effect of the van der Waals interactions on the electronic structure, the relevant structure was also optimized with B3LYP-D2, PBE-D2, and optB88-vdW functionals. The refined crystal structure was confirmed by the DFT calculations. The best agreement with the experimental structure was achieved by optB88-vdW functional. (C) 2019 International Centre for Diffraction Data.