Abstract: Tests were conducted to measure the quantity of NH⁴₊-N sorption at equilibrium by vermiculite minerals in NH₄Cl solution under constant pH and temperature conditions with objective to providing theoretical argument and as well basic parameters for use of vermiculite to remove NH⁴₊-N in wastewater treatment. Analytical results showed that the relation of NH⁴₊-N sorption quantity by vermiculite minerals at equilibrium Qe with initial solution NH⁴₊-N concentration C and sorbent quantity W can be described using Langmuir equation, with a common thermal sorption form: Q_e = q_mCW/q_m(K_W+W) +C. The maximum sorption quantity per unit sorbent qm and the medium coefficient K_W are constant terms independent of both C and W, of which qm represents unit medium sorption capacity while K_W reflects the affinity of sorbent to NH⁴₊-N.