Indeed, gifts (donations) between spouses may be freely revoked by the donor at any time, and the right to revoke cannot be waived (Article 1765(1) of the Portuguese Civil Code). This is one of the most significant features of this legal regime, departing from the general rule that contracts may only be revoked by mutual agreement.
Legal scholars generally understand that the legislature's intention is to prevent divorce from becoming a means of acquiring assets beyond the fair division of property accumulated through the spouses' joint efforts during the marriage.
Accordingly, the donor may revoke the gift at any time, without being required to provide any justification.
It should also be emphasized that gifts between spouses lapse upon divorce, a consequence that is often unknown to the parties involved and has given rise to considerable litigation.
In the event of divorce, each spouse generally forfeits any benefits (including gifts) that he or she has received or was entitled to receive from the other spouse, or from a third party, where such benefits were made in contemplation of the marriage or in consideration of the marital relationship (Article 1791 of the Portuguese Civil Code). However, the donor may stipulate that the benefit should instead pass to the children of the marriage. In simple terms, gifts between spouses are not necessarily preserved following a divorce and may be revoked.
In light of the above, the answer to the question posed is affirmative: gifts between spouses may be revoked by the donor.