We investigate self-verifying nondeterministic finite automata, in the case of unary symmetric difference nondeterministic finite automata (SV-XNFA). We show that there is a family of languages $$\mathcal {L}_{n\ge 2}$$ which can always be represented non-trivially by unary SV-XNFA. We also consider the descriptional complexity of unary SV-XNFA, giving an upper and lower bound for state complexity.