Considered one of the world's most corrupt countries, according to Transparency International's corruption perceptions index, oil-producing Equatorial Guinea's football team are ranked 119th in the world by governing body FIFA.
The match will be followed three days later by a friendly against South Africa at the Soccer City stadium in Johannesburg, scene of Spain's maiden World Cup triumph in 2010.
Coach Vicente del Bosque is due to announce his squad for the two games on Thursday, when he may call up Atletico Madrid's Brazil-born striker Diego Costa for the first time.
The in-form Costa, who has dual Brazilian and Spanish nationality, last month confirmed he wanted to play for Spain rather than the country of his birth.
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Spain secured their place at next year's World Cup finals in Brazil when they finished top of European qualification Group I ahead of France.
(Reporting by Iain Rogers, editing by Clare Fallon)
