We present a new code to evaluate thermoelectric and electronic transport properties of extended systems with a maximally-localized Wannier function basis set. The semiclassical Boltzmann transport equations for the homogeneous infinite system are solved in the constant relaxation-time approximation and band energies and band derivatives are obtained via Wannier interpolations. Thanks to the exponential localization of the Wannier functions obtained, very high accuracy in the Brillouin zone integrals can be achieved with very moderate computational costs. Moreover, the analytical expression for the band derivatives in the Wannier basis resolves any issues that may occur when evaluating derivatives near band crossings. The code is tested on binary and ternary skutterudites CoSb3 and CoGe3/2 S-3/2. Program summary Program title: BoltzWann Catalogue identifier: AEQX_v1_0 Program summaiy URL: http://cpc.cs.qub.ac.uk/summaries/AEQX_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 710 810 No. of bytes in distributed program, including test data, etc.: 8 337 000 Distribution format: tar.gz Programming language: Fortran 90. Computer: Any architecture with a Fortran 90 compiler. Operating system: Linux, Windows, Solaris, AIX, Tru64 Unix, OSX. Has the code been vectorized or parallelized?: Yes. RAM: The example requires approximately 10 MB. Classification: 7.3, 7.9. External routines: BLAS and LAPACK (available on http://www.netlib.org/); MPI libraries (optional) for parallel execution Nature of problem: Obtain electronic and thermoelectric transport properties for crystals. Solution method: The Boltzmann transport equations in the constant relaxation-time approximation are used. These equations require the integration of the band velocities over all the Brillouin zone; this is done numerically on a sufficiently dense k grid. Band energies and band derivatives are obtained by interpolation using the maximally-localized Wannier functions basis obtained with a preliminary run of the Wannier90 code. Unusual features: The maximally-localized Wannier functions interpolation scheme allows the use of analytical formulas (instead of finite-difference methods) to obtain the band derivatives. Additional comments: This is a package that is tightly integrated with the Wannier90 code (http://www.wannier.org). The Wannier90 code is included in the distribution package. Running time: The example runs (in its serial version) in less than 2 min. (C) 2013 Elsevier B.V. All rights reserved.