Heavy metals in wastewater possess a serious threat to the environment and its removal from water required significant consideration. In this regard several techniques were employed for its remediation however, the low efficiency and high toxicity of the existing adsorbents compel the researcher to investigate/develop sustainable adsorbents. Therefore, in this study the hydrophobic ionic liquid, trihexyltetradecylphosphonium dicyanamide ([PC6C6C6C14][-N(CN)2-)] is used for the removal of heavy metal, Thallium (Tl) from aqueous solution. The results showed that [PC6C6C6C14][-N(CN)2-] have the potential to adsorbed Thallium from aqueous solution with adsorption capacity of (180 mg/g). Moreover, the removal efficiency of the [PC6C6C6C14][-N(CN)2-] was also investigated and it was noticed that [PC6C6C6C14][-N(CN)2-] have the ability to remove more than 85% Thallium from aqueous solution. Hence, the result presented in current study showed that ILs have the potential to effectively replace the conventional toxic adsorbents.