Yes — and the precision is the apologetic payoff. A Catholic may marry an Orthodox Christian; the marriage is fully valid and recognized, and the children of such a union are not in doubt. Because the Orthodox spouse is a baptized non-Catholic, the Church classifies it as a “mixed marriage,” which triggers specific norms: the permission of the local bishop, certain promises about the children’s faith, and rules about the form of the celebration.

The single most important — and most misunderstood — point flows directly from the fact that the Orthodox have valid sacraments and orders. For a marriage between a Catholic and an Eastern (Orthodox) Christian, the Catholic canonical form — a wedding before a Catholic minister — is required only “for liceity”; “for validity, however, the presence of a sacred minister is required.” In plain terms: a Catholic–Orthodox wedding celebrated by an Orthodox priest is valid — absent any other impediment, such as a prior bond. The absence of Catholic form makes it illicit, not null — a deliberately more lenient rule than for marriages with Protestants, whose form is required for validity.

What the law does ask is straightforward and pastoral. The Catholic party seeks the bishop’s permission and promises “to do all in his or her power so that all offspring are baptized and brought up in the Catholic Church”; the Orthodox party is simply informed of that promise, not required to make one; and both are instructed on the meaning of marriage. Where the couple weds in the Orthodox church, the Catholic’s bishop can dispense from Catholic form, so the marriage is licit as well as valid.

Two honest notes. The Orthodox Church has its own rules, which Catholic law does not govern — most Orthodox jurisdictions require the wedding to take place in the Orthodox church to recognize it as sacramental, so the common path is an Orthodox-church wedding with a Catholic dispensation from form, valid for both. And the real friction is the children: each Church hopes they will be raised in its communion, and the law obliges the Catholic to act in good faith, not to guarantee an outcome. None of this is an obstacle to the marriage; the Church positively provides for it.