He belonged to a wealthy middle-class family of Huguenot persuasion; the name des Réaux he derived from a small property purchased by him in 1650. When he was about eighteen years of age he was sent to Italy with his brother François, abbé Tallemant. On his return to Paris, Tallemant took his degrees in civil and canonical law, and his father secured for him the position of conseiller au parlement. The profession was distasteful to him, and he decided to ensure himself a competence by marriage with his cousin Elisabeth de Rambouillet. His half-brother had married a d'Angennes, and this connection secured for Tallemant an introduction to the Hôtel de Rambouillet.
Madame de Rambouillet was no admirer of Louis XIII, and she gratified Tallemant's curiosity with stories of the reigns of Henry IV and Louis XIII of real historical value. But the society of the Hôtel de Rambouillet itself opened a field for his acute and somewhat malicious observation. In the Historiettes he gives finished portraits of Voiture, Balzac, Malherbe, Chapelain, Valentin Conrart and many others; Blaise Pascal and Jean de la Fontaine appear in his pages; and he chronicles the scandals of which Ninon de l'Enclos and Angélique Paulet were centres.
They are invaluable for the literary history of the time. It has been said that the malicious intention of his work may be partly attributed to his bourgeois extraction and that the consequent slights he received are avenged in his pages, but independent testimony has established the substantial correctness of his statements. In 1685 he was converted to Catholicism. It seems that the change was not entirely disinterested, for Tallemant, who had suffered considerable pecuniary losses, soon after received a pension of 2000 livres. He died in Paris on the 6th of November 1692.
Des Réaux was a poet of some merit and contributed to the Guirlande de Julie, but it is by his Historiettes that he is remembered. The work remained in manuscript until it was edited in 1834-6 by MM. de Châteaugiron, Jules Taschereau and LJN de Monmerqué, with a notice on Tallemant by Monmerqué. A third edition (6 vols. 1872) contains a notice by Paulin Paris. Tallemant had begun Mémoires pour Ia régence d'Anne d'Autriche, but the manuscript has not been found.