The work that is now presented, under the title, “The legal regime of public debt in the Mozambican legal order” constitutes an abstract reflection on the constitutional and legal discipline applicable to public debt in Mozambique, which, being applicable to concrete cases of public indebtedness, possibly already established, or, present and future, addresses legal issues that extend from training to the extinction of the public debt, including the concept, possible classifications, legal nature, conditions of invalidity and ineffectiveness, highlighting the vices of usurpation of power, incompetence, misuse of power, violation of the law and formal defects and deducting the respective consequences, namely the non-existence and nullity of public debt, from which the Mozambican State is not bound to comply with the invalid debt contracted with private law subjects, internal or external, and the duty to comply with it when entered into with States and International Public Law Organizations.