The current work comprises the investigation of biodiesel production from linseed oil using TiO2 and a potassium L-tartrate monobasic (C4H5KO6)-modified TiO2 nanocatalyst. Different amounts of C4H5KO6 were considered for TiO2 modification. The nanocatalyst TiO2-0.5C(4)H(5)KO(6) (1:0.5 molar ratio) showed the best conversion rate for biodiesel production. The nanocatalyst was characterized by FTIR, XRD, TEM, BET, and XPS, and the Hammett indicator benzenecarboxylic acid titration method was used for basicity measurement. The biodiesel was characterized by GC-MS and H-1 and C-13 NMR Furthermore, the optimum reaction parameters for transesterification reaction were analyzed, and the yield was determined by GC-MS and H-1 NMR. The maximum yield of 98.5% was obtained with 6 wt% catalyst amount and 1:6 oil-to methanol ratio at 60 degrees C for 3 h. The properties of biodiesel obtained from linseed oil were determined using the EN 14214/ASTM D6751 method. The reusability of the catalyst was tested up to five cycles and showed promising results.