Post-mix burner extending between a burner bottom and a burner top and in a longitudinal direction between a first burner end and a second burner end, the burner presenting: • a central dividing wall extending from the burner bottom to the burner top and, in the longitudinal direction, from the first burner end to the second burner end, the central dividing wall comprising, towards the burner top, a wall head extending in the longitudinal direction and terminating in an ejection surface at the burner top; • a first inlet compartment adjacent the burner bottom on a first side of the central dividing wall and a second inlet compartment adjacent the burner bottom on a second side of the central dividing wall opposite the first side; • a first outlet compartment adjacent the burner top on the first side of the central dividing wall and a second outlet compartment adjacent the burner top on the second side of the central dividing wall, the first inlet compartment being separated from the first outlet compartment by a first separation plate extending from the central dividing wall on the first side thereof and the second inlet compartment being separated from the second outlet compartment by a second separation plate extending from the central dividing wall on the second side thereof; • a first fluid inlet leading into the first inlet compartment and adapted for the supply of a first fluid into the first inlet compartment from outside the burner and a second fluid inlet leading into the second inlet compartment and adapted for the supply of a second fluid into the second inlet compartment from outside the burner; whereby • the first separation plate presents a first set of multiple first through passages fluidly connecting the first inlet compartment to the first outlet compartment, said first set of first through passages extending in the longitudinal direction; • the second separation plate presents a second set of multiple second through passages fluidly connecting the second inlet compartment to the second outlet compartment, said second set of second through passages extending in the longitudinal direction; • the wall head presents a first set of first outlet passages and a second set of second outlet passages terminating respectively in first ejection openings and second ejection openings in the ejection surface, the first outlet passages fluidly connecting the first outlet compartment to an area downstream of the burner top and the second outlet passages fluidly connecting the second outlet compartment to said downstream area, the first and second ejection openings (100, 200) each extending in the longitudinal direction in the ejection surface. • a central dividing wall extending from the burner bottom to the burner top and, in the longitudinal direction, from the first burner end to the second burner end, the central dividing wall comprising, towards the burner top, a wall head extending in the longitudinal direction and terminating in an ejection surface at the burner top; • a first inlet compartment adjacent the burner bottom on a first side of the central dividing wall and a second inlet compartment adjacent the burner bottom on a second side of the central dividing wall opposite the first side; • a first outlet compartment adjacent the burner top on the first side of the central dividing wall and a second outlet compartment adjacent the burner top on the second side of the central dividing wall, the first inlet compartment being separated from the first outlet compartment by a first separation plate extending from the central dividing wall on the first side thereof and the second inlet compartment being separated from the second outlet compartment by a second separation plate extending from the central dividing wall on the second side thereof; • a first fluid inlet leading into the first inlet compartment and adapted for the supply of a first fluid into the first inlet compartment from outside the burner and a second fluid inlet leading into the second inlet compartment and adapted for the supply of a second fluid into the second inlet compartment from outside the burner; • the first separation plate presents a first set of multiple first through passages fluidly connecting the first inlet compartment to the first outlet compartment, said first set of first through passages extending in the longitudinal direction; • the second separation plate presents a second set of multiple second through passages fluidly connecting the second inlet compartment to the second outlet compartment, said second set of second through passages extending in the longitudinal direction; • the wall head presents a first set of first outlet passages and a second set of second outlet passages terminating respectively in first ejection openings and second ejection openings in the ejection surface, the first outlet passages fluidly connecting the first outlet compartment to an area downstream of the burner top and the second outlet passages fluidly connecting the second outlet compartment to said downstream area, the first and second ejection openings (100, 200) each extending in the longitudinal direction in the ejection surface.