While you cannot find an online catalog for Walthers trains at Walthers.com, you can order a catalog from the website for shipping to your home. As of June 2015, this website offers more than a dozen different Walthers train catalogs for shipping.
For some of the catalogs, such as the 2015 Atlas All-Scale Catalog, the 2015 Bachmann Catalog and a few others, there is no charge for ordering and receiving them. Other catalogs require a payment between $3 and $14.99 to receive a copy. While there is not a viewable catalog on the company's website, the site does offer enthusiasts a chance to browse the company's product lines.