Abstract Let ( hyp o n , ♯ ) be the hypoplactic monoid of finite rank n with Schützenberger’s involution ♯ . In this paper, we exhibit a faithful representation of ( hyp o n , ♯ ) as an involution monoid of upper triangular matrices over any semiring from a large class including the tropical semiring under the skew transposition. We then give a transparent combinatorial characterization of the word identities satisfied by ( hyp o n , ♯ ) . Further, we prove that ( hyp o n , ♯ ) is non-finitely based if and only if n = 2, 3 and give a polynomial time algorithm to check whether a given word identity holds in ( hyp o n , ♯ ) .Communicated by Scott Chapman [ABSTRACT FROM AUTHOR]