A new institutional clinical trial assessed the improvement of sleep disorders in 40 children with autism treated by immediate-release melatonin formulation in different regimens(0.5 mg, 2 mg, and 6 mg daily) for one month. The objectives of present study were to(i) prepare low-dose melatonin hard capsules for pediatric use controlled by two complementary methods and(ii) carry out a stability study in order to determine a use-bydate. Validation of preparation process was claimed as ascertained by mass uniformity of hard capsules.Multicomponent analysis by attenuated total reflectance Fourier transformed infrared(ATR-FTIR) of melatonin/microcrystalline cellulose mixture allowed to identify and quantify relative content of active pharmaceutical ingredients and excipients. Absolute melatonin content analysis by high performance liquid chromatography in 0.5 mg and 6 mg melatonin capsules was 93.6% ± 4.1% and 98.7% ± 6.9% of theoretical value, respectively. Forced degradation study showed a good separation of melatonin and its degradation products. The capability of the method was 15, confirming a risk of false negative < 0.01%. Stability test and dissolution test were compliant over 18 months of storage with European Pharmacopoeia. Preparation of melatonin hard capsules was completed manually and melatonin in hard capsules was stable for 18 months, in spite of low doses of active ingredient. ATR-FTIR offers a real alternative to HPLC for quality control of highdose melatonin hard capsules before the release of clinical batches. A new institutional clinical trial assess the improvement of sleep disorders in 40 children with autism treated by immediate-release melatonin formulation in different regimens (0.5 mg, 2 mg, and 6 mg daily) for one month. The objectives of present study were to ( i) prepare low-dose melatonin hard capsules for pediatric use controlled by two complementary methods and (ii) carry out a stability study in order to determine a use-bydate. Validation of preparation process was claimed as ascertained by mass uniformity of hard capsules. Multicomponent analysis by attenuated total reflectance Fourier transformed infrared (ATR-FTIR) of melatonin / microcrystalline cellulose mixture allowed identify and quantify relative content of active pharmaceutical ingredients and excipients. Absolute melatonin content analysis by high performance liquid chromatography in 0.5 mg and 6 mg melatonin The capsules were 93.6% ± 4.1% and 98.7% ± 6.9% of the theoretical value, respectively. Forced degradation study showed a good separation of melatonin and its degradation products. The capability of the method was 15, confirming a risk of false negative <0.01%. Stability test and dissolution test were compliant over 18 months of storage with European Pharmacopoeia. Preparation of melatonin hard capsules was completed manually and melatonin in hard capsules was stable for 18 months, in spite of low doses of active ingredient. ATR-FTIR offers a real alternative to HPLC for quality control of high dose melatonin hard capsules before the release of clinical batches.