An infusion device for preparing a food product from single serving capsules, comprising: - an infusion chamber formed by a first portion (17; 217) and a second portion (19; 219), movable with respect to each other along an opening and closing direction; - a first duct (47; 247) for feeding an infusion liquid in said infusion chamber (17, 19; 217, 219); - a second duct (33; 233) for dispensing the food product from the infusion chamber; - a pair of oscillating arms (51; 251), movable with respect to at least one of said first and second portion of the infusion chamber, along said opening and closing direction, and provided with retaining members (57; 257) for retaining a capsule in a space between the first and the second portion of the infusion chamber, when said infusion chamber is open and to insert said capsule inside the infusion chamber; - divaricating members (63; 217A) for causing reciprocal divarication of the two arms (51; 251) and of the respective retaining members (57; 257) and the release of the capsule inside the infusion chamber; - in one of said first and second portion of the infusion chamber, an ejector (35; 235) for ejecting the capsule from the infusion chamber when the infusion cycle is ended; - members for temporarily deactivating said retaining members (57; 217) and said arms (51; 251) when the first and the second portion of the infusion chamber are reciprocally withdrawn, in a deactivated condition said retaining members (57; 257) not interfering with the capsule during at least a part of the opening movement of the infusion chamber to eject the used capsule from the infusion chamber when an infusion cycle is ended; wherein the first portion (17; 217) of the infusion chamber is fixed and the second portion (19; 219) of the infusion chamber is movable with respect to a bearing frame (13; 213); characterized in that said arms (51; 251) are constrained to the second portion (19; 219) of the infusion chamber and movable with respect thereto according to said opening and closing direction, so that when said second portion (19; 219) of the infusion chamber is moved toward the closing position, the arms (51; 251) follow the movement of the second portion (19; 219) of the infusion chamber until a stop position, passing through a position of release of the capsule in the first portion (17; 217) of the infusion chamber, the infusion chamber being closed through an over travel movement of the second portion (19; 219) of the infusion chamber in said opening and closing direction, when the arms (51; 251) achieved their stop position. - an infusion chamber formed by a first portion (17; 217) and a second portion (19; 219), movable with respect to each other along an opening and closing direction; - a first duct (47; 247) for feeding an infusion liquid in said infusion chamber (17, 19; 217, 219); - a second duct (33; 233) for dispensing the food product from the infusion chamber; - a pair of oscillating arms (51; 251), movable with respect to at least one of said first and second portion of the infusion chamber, along said opening and closing direction, and provided with retaining members (57; 257) for retaining a capsule in a space between the first and the second portion of the infusion chamber, when said infusion chamber is open and to insert said capsule inside the infusion chamber; - divaricating members (63; 217A) for causing reciprocal divarication of the two arms (51; 251) and of the respective retaining members (57; 257) and the release of the capsule inside the infusion chamber; - in one of said first and second portion of the infusion chamber, an ejector (35; 235) for ejecting the capsule from the infusion chamber when the infusion cycle is ended; - members for temporarily deactivating said retaining members (57; 217) and said arms (51; 251) when the first and the second portion of the infusion chamber are reciprocally withdrawn, in a deactivated condition said retaining members (57; 257) not interfering with the capsule during at least a part of the opening movement of the infusion chamber to eject the used capsule from the infusion chamber when an infusion cycle is ended; wherein the first portion (17; 217) of the infusion chamber is fixed and the second portion (19; 219) of the infusion chamber is movable with respect to a bearing frame (13; 213); characterized in that said arms (51; 251) are constrained to the second portion (19; 219) of the infusion chamber and movable with respect thereto according to said opening and closing direction, so that when said second portion (19; 219) of the infusion chamber is moved toward the closing position, the arms (51; 251) follow the movement of the second portion (19; 219) of the infusion chamber until a stop position, passing through a position of release of the capsule in the first portion (17; 217) of the infusion chamber, the infusion chamber being closed through an over travel movement of the second portion (19; 219) of the infusion chamber in said opening and closing direction, when the arms (51; 251) achieved their stop position.