It is disclosed an electronic system (1 ) to control the acquisition of an electrocardiogram. The system comprises a portable electronic device (2) and a mobile electronic device (3). The mobile electronic device comprises an optical device (3-1) for acquiring real-time images of a portion of a human body, comprises a screen (3-2) and comprises a processing unit (3-3) connected to the optical device and to the screen. The portable electronic device (2) comprises a first (2-1), a second (2-2) and a third (2-3) electrode configured to generate a first (S1_r), a second (S2_r) and a third (S3_r) detecting electrical signal respectively representing the current generated on the skin by the activity of the heart of a human being in the respective points wherein the first, second and third electrodes are positioned on said portion of the human body. The processing unit of the mobile electronic device comprises an electrodes placement guiding module (3-3.1) for the first, second and third electrode. The electrodes placement guiding module is configured to receive a plurality of real-time images (l1, I2 ... In) representing the portion of the human body, is configured to identify a feature of the portion of the human body within at least a part of said plurality of images, it is configured to calculate, as a function of the identified feature, the positions wherein to apply the first, second and third electrode on the portion of the human body and it is configured to generate a driving signal (S_pl) carrying information indicating the calculated positions wherein to apply the first, second and third electrode. The screen is configured to receive said driving signal and it is configured to display a real-time image (l_ps_el) representing said portion of the human body and further comprises a first positioning mark (A1), a second positioning mark (A2) and a third positioning mark (A3) representing the positions wherein to apply the first, second and third electrode respectivel
