A new procedure was studied to obtain concentrated methane hydrates in bulk, at medium-low pressure, avoiding the use of the spray process. Methane hydrate was formed at about 5 MPa and 2 °C in a reaction calorimeter with the volume of two liters. The clathrate concentration was about 30% and the final reactor pressure was 2.7 MPa. Any further repressurization at 2 °C had no noticeable effect on the hydrate formation. However, by repressurizing the vessel again to 4 MPa and increasing the temperature near the decomposition value (about 6° C) more clathrate was formed. Repressurizing again the reactor at 4 MPa and controlling the temperature at the same level, a concentration of 88% hydrate in the bulk was reached. Respect to the hydrate produced by the spray process, this procedure takes more time, but it can be sped up and made continuous by using teo reaction vessels, one for hydrate formation and the other for hydrate concentration. The advantage is the production of concentrated hydrates, by a simple equipment, working at relatively low pressures.