You should consult the Brazilian Register Office ("Cartório de Registro Civil") or your church in Brazil where you intend to marry, as requirements vary from place-to-place. However, here's a guide on the sort of documents that they may require from you.

If you’re unmarried

• Birth certificate (for British citizens, Full Birth Certificate) legalised by the Brazilian Consulate in the UK and translated into Portuguese by a Sworn Translator in Brazil.
• Non-impediment Certificate ("Atestado de Estado Civil")

This document can be issued  from the Register Office at your local Town Hall - a Notarised Declaration ("Affidavit") signed by two persons before the Notary public, declaring that they have known the applicant for more than two years and that to their knowledge there is no impediment to his/her marriage or at the British Consulate in Brazil. (see Notarial Services - No Impediment.)

• Residence Certificate (proof of residence). 
• Passport or Identity Card (original and translated by a Sworn Translator in Brazil).
• Power of Attorney (Procuração), if applicable.

If you’re divorced

• Birth certificate (for British citizens, Full Birth Certificate) legalised by the Brazilian Consulate in the UK and translated into Portuguese by a sworn translator in Brazil.
• Divorce decree "Nisi Absolute" and original Marriage Certificate legalised by the Brazilian Consulate in the UK and translated into Portuguese by a sworn translator.

When divorced abroad from a Brazilian citizen, you may need to present a document called "homologação de sentença estrangeira".

• Passport or Identity Card (original and translated by a Sworn Translator in Brazil)
• Power of Attorney ("Procuração) if applicable.
• Non-impediment Certificate ("Atestado de Estado Civil").

This document can be issued  from the Register Office at your local Town Hall - a Notarised Declaration ("Affidavit") signed by two persons before the Notary public, declaring that they have known the applicant for more than two years and that to their knowledge there is no impediment to his/her marriage or at the British Consulate in Brazil. (see Notarial Services - No Impediment.)

If you’re widowed  

• Birth certificate (for British citizens, Full Birth Certificate) legalised by the Brazilian Consulate in the UK and translated by a Sworn Translator in Brazil.
• Spouse's Death Certificate and original Marriage Certificate legalised by the Brazilian Consulate in the UK and translated by a Sworn Translator in Brazil.
• Residence Certificate (proof of residence).
• Passport or Identity Card (original and main page translated by a Sworn Translator in Brazil).
• Power of Attorney ("Procuração") if applicable.
• Non-impediment Certificate ("Atestado de Estado Civil").

To be valid in Brazil, documents issued abroad must be legalised by the Brazilian consulate at the place where documents were issued. Once legalised, documents must be translated into Portuguese by a sworn translator in Brazil.

This document can be issued  from the Register Office at your local Town Hall - a Notarised Declaration ("Affidavit") signed by two persons before the Notary public, declaring that they have known the applicant for more than two years and that to their knowledge there is no impediment to his/her marriage or at the British Consulate in Brazil. (see Notarial Services - No Impediment.)