This article presents a study on heat transfer in condensation of pure and mixtures of hydrocarbons in a compact welded plate heat exchanger Three pure fluids (pentane, butane, and propane) and two mixtures (butane + propane) have been used. The operating pressure ranges from 1.5 to 18 bar For pure fluids, two heat transfer mechanisms have been identified. For low Reynolds numbers, the condensation occurs almost filmwise and the heat transfer coefficient decreases with increasing Reynolds number For higher values of the Reynolds number, the heat transfer coefficient increases gently. The transition between the two regimes is between Re = 100 and 1,000 and depends oil the operating conditions. For mixtures, the behavior is different. For low Reynolds numbers, mass transfer affects heat transfer and reduces the heat transfer coefficient by a factor of up to 4. Correlations for filmwise and in-tube condensation do not predict the results accurately, and a specific correlation is proposed for pure fluid condensation. For mixtures, the condensation curve method does not allow mass transfer effects to be taken into account, and more work is required to establish all accurate predictive model.