L‐proline tartrate (LPT), 1 and 2 mol% of lanthanum chloride‐ (LaCl3‐) doped LPT single crystals have been synthesized and grown using a slow evaporation solution method at room temperature. The crystals have undergone different characterization studies to test their suitability for device fabrication. The single crystal X‐ray diffraction studies have revealed that both 1 and 2 mol% of LaCl3‐doped LPT single crystals have been crystalized monoclinic crystal structure and space group P21. The UV‐Vis‐NIR spectrum analysis has shown that pure, 1, and 2 mol% of LaCl3‐doped LPT single crystals have good optical transparency in the entire visible and near IR region. The optical band gap energy for pure, 1 and 2 mol% of LaCl3‐doped LPT single crystals to be 4.9, 5, and 5.1 eV, respectively. The energy dispersive X‐ray analysis confirmed that LaCl3 has been incorporated into LPT crystal. The second harmonic generation (SHG) efficiency for 1 and 2 mol% of LaCl3‐doped LPT single crystals has been tested and found to be 1.27 and 1.6 times greater than that of the reference KDP crystal, respectively.