Abstract: In a process for the preparation of lactam from cycloalkanone comprising reacting said alkanone with hydroxylamine sulfate to form the corresponding cycloalkanone oxime followed by Beckman rearrangement to yield said lactam and neutralization of the sulfuric acid formed by ammonia whereby ammonium sulfate is formed as a byproduct, the improvement which comprises reacting said ammonium sulfate with an alkaline-earth metal oxide or hydroxide to form an alkaline earth metal sulfate and ammonia, heating said alkaline-earth metal sulfate to decompose it into said alkaline-earth metal oxide and sulfur dioxide and/or sulfur trioxide, converting said sulfur dioxide and/or sulfur trioxide into sulfuric acid, whereby said sulfuric acid and said ammonia are capable of reuse in said process.