We consider the integer Chebyshev problem, that of minimizing the supremum norm over polynomials with integer coefficients on the interval [0, 1]. We implement algorithms from semi-infinite programming and a branch and bound algorithm to improve on previous methods for finding integer Chebyshev polynomials of degree n. Using our new method, we found 16 new integer Chebyshev polynomials of degrees in the range 147 to 244.Here this constant is explicitly computable to an arbitrary number of digits. See [11,18] for details. In [5] it was shown that the lower bound coming from this infinite family is in fact not best possible. That is, there exists an ǫ > 0 such that t Z ([0, 1]) ≥ 0.4207263 · · · + ǫ. At the time no non-trivial lower bound for ǫ was determined. Pritsker showed in [19], by means of weighted potential theory, that t Z ([0, 1]) ≥ 0.4213. Generalizations of these Gorshkov-Wirsing polynomails were considered in [15].Given the submultiplicative nature of t Z,n (I) we have t Z (I) ≤ t Z,n (I) for all n. This gives a simple method to find an upper bound for t Z (I); find large degree polynomials with small supremum norm. In [5] a set of 9 polynomials p i (x) and exponents a i were found such that the resulting polynomial P (x) = p 1 (x) a1 . . . p 9 (x) a9 had small supremum norm. This was used to show that t Z ([0, 1]) ≤