Highly transparent single crystals of Li₂B₄0₇ ie. lithium tetraborate (L TE3) doped with Cu (0.25 wt. %) and Cu & In (0.5 wt. % each) were grown by the Czochralski method, The Li₂B₄0₇: Cu and Li₂B₄0₇:Cu, In crystals were studied using thermoluminescence (TL) technique, The TL readout of Li₂B₄0₇:Cu crystals showed two well-defined glow peaks at 130°C and 235°C for heating rate of 4K/s, whereas in LTB:Cu. In another shoulder peak on low temperature side of the main peak is seen, The TL sensitivities of LTB:Cu and LTB:Cu. In were found to be 3.3 and 6 times to that of TLD-100 respectively, Both the LTB:Cu and L B:Cu. In crystals exhibit a linear TL dose response in the dose range from 1 mGy to 1 kGy, The single crystal of Li₂B₄0₇: Cu. ln could become a potential TL phosphor for medical and clinical dosimetry owing to its very good sensitivity and excellent tissue equivalence