The present invention relates to a dishwashing machine (100) comprising a washing unit (1), a rinsing unit (2) and a heat pump circuit (3) in which a working fluid flows, wherein a washing chamber (10) and a rinsing chamber (20) are defined in said washing unit (1) and in said rinsing unit (2), respectively, said heat pump circuit (3) exchanging heat with a vapour flow (V) from said rinsing unit (2) and/or from said washing unit (1), characterized in that it further comprises a secondary heating circuit (6) heating water for treating dishware in said dishwashing machine (100) by means of a secondary fluid circulating in said secondary heating circuit (6), said secondary heating circuit (6) comprising a secondary heat exchange unit (60) thermally coupled with said heat pump circuit (3) for heating said secondary fluid. The invention also relates to a method for operating a dishwashing machine (100) including a washing unit (1), a rinsing unit (2), a heat pump circuit (3) and a secondary heating circuit (6), wherein a washing chamber (10) and a rinsing chamber (20) are defined in said washing unit (1) and in said rinsing unit (2), respectively, said heat pump circuit (3) exchanging heat with a vapour flow (V) from said rinsing unit (2 and/or from said washing unit (1), said method comprising: heating a secondary fluid circulating in said secondary heating circuit (6) by means of said heat pump circuit (3); heating water for treating dishware in said dishwashing machine (100) by means of said secondary fluid heated by said heat pump circuit (3).