The article compares mediation in administrative proceedings in Poland and Hungary. Both introduced it into their general codes of administrative procedure (Hungary in 2005, Poland in 2017) with opposite trajectories: Poland retained and recently expanded the institution, Hungary de-institutionalised it as a general tool in 2018, confining it to sectoral regimes. Using the dogmatic and comparative methods, it reconstructs both models and confronts their design with the evidence of practice. The decisive constraints prove structural, not technical: the principle of legality narrows the space for genuine negotiation, procedural time limits penalise consensual methods, and the culture of unilateral decision-making discourages authorities. Formal institutionalisation, unaccompanied by informational, organisational and cultural measures, does not translate into actual use.