Century Aluminum Company - Company Announcement

USW Rejects Century Aluminum's Contract Offer

Company Will Begin Lockout of USW on May 12, 2015

CHICAGO, IL--(Marketwired - May 12, 2015) - Century Aluminum of Kentucky
General Partnership (the "Company"), a subsidiary of Century Aluminum Company
(NASDAQ:CENX) ("Century"), today announced that members of USW Local 9423 at
its Hawesville, Kentucky smelter rejected the Company's modified Last, Best,
and Final ("LBF") offer Monday night, May 11, 2015. As a result, a lockout is
scheduled to commence at 8 a.m. CDT on May 12, 2015. The lockout will allow
other personnel to maintain uninterrupted plant operations, which is required
in the continuous-flow operation of an aluminum smelter. The smelter is fully
prepared for the lockout and is expected to continue to operate safely and at
full production. "Unfortunately the members rejected the contract, which leaves us with no
choice but to lock out union represented workers," said John Hoerner, Sr.
Vice-President, North America Operations. "We negotiated in earnest for greater
than three months and reached three agreements with the union's negotiating
committee, but all were rejected by the membership. In essence, we are out of
options."

The Company's final offer included pay increases of more than 14 percent during
the five-year period, provided fixed costs for health insurance, lower
out-of-pocket maximum, and new language on overtime. 

A dedicated website -- www.cakycbaupdate.com -- was developed to keep
employees, families, community members and others apprised of the latest
developments relating to the Hawesville facility. None of Century's other
operations or facilities are affected by the lockout of Local 9423 in
Hawesville and Century expects its cash operating costs for the second quarter
of 2015 to be in-line with the estimates previously provided. 

About Century Aluminum
Century Aluminum Company owns primary aluminum capacity in the United States
and Iceland. Century's corporate offices are located in Chicago, IL. 

Visit www.centuryaluminum.com for more information.

Certified Advisors for the First North market of the OMX Nordic Exchange
Iceland hf. for Global Depositary Receipts in Iceland: 
Atli B. Gudmundsson, Senior Manager -- Corporate Finance, Landsbankinn hf.
Steingrimur Helgason, Director -- Corporate Finance, Landsbankinn hf.