The present invention refers to a support frame (2) for wall-mounting at least one electrical apparatus, the frame (2) comprising:--a frame body (7) fixable to the wall and developing about a window (9) defining a mounting seat adapted for receiving and holding said at least one electrical apparatus; and--fixing means (12) for removably fixing a cover plate (3) to the support frame (2). The support frame (2) is characterised in that the fixing means includes at least one fixing channel (12) exhibiting an end jointed to an opening (13) obtained in the frame body (7), the fixing channel (12) being such as to be capable of receiving, through the opening (13), a corresponding fixing tongue (4), provided in the cover plate (3), the fixing channel (12) including therein relief means (14) that can face a surface (31) of the tongue (4) and pushing means (20, 21) adapted for acting on the fixing tongue (4) for engaging pressure-wise said surface (31) of the tongue against said relief means (14) of the channel (12).