The static magnetic and dynamic properties of the compound (NH3)2(CH2)3CoCl4 are investigated in the temperature interval 0.5–50K. It is shown that at TN=2.05K this compound undergoes a transition to a magnetically ordered antiferromagnet state. A distinctive feature of this compound is the presence of temperature hysteresis at the transition to the ordered state (corresponding to a first-order magnetic phase transition) and of a spontaneous magnetic moment along the x axis. The paramagnetic Curie temperatures are determined. The frequency–field curves of the AFMR spectrum in the xy plane are investigated at a temperature below TN. The main magnetic parameters of the biaxial AFM — the value of the low-frequency gap and the effective magnetic anisotropy field — are determined.