**EXHIBIT 31.1**
**SECTION 302 CERTIFICATION**
I, Kevin Armstrong, certify that:
1.  I have reviewed this quarterly report on Form 10-Q of Cosi, Inc; 2.  Based on my knowledge, this report does not contain any untrue statementof a material fact or omit to state a material fact necessary to make thestatements made, in light of the circumstances under which such statements weremade, not misleading with respect to the period covered by this report; 3.  Based on my knowledge, the financial statements, and other financialinformation included in this report, fairly present in all material respects thefinancial condition, results of operations and cash flows of the registrant asof, and for, the periods presented in this report; 4.  The registrant’s other certifying officer(s) and I are responsible forestablishing and maintaining disclosure controls and procedures (as defined in ExchangeAct Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (asdefined in Exchange Rules 13a-15(f) and 15d-15(f), for the registrant and have:
 (a)  Designed such disclosure controls and procedures, or caused suchdisclosure controls and procedures to be designed under our supervision, to ensurethat material information relating to the registrant, including its consolidatedsubsidiaries, is made known to us by others within those entities, particularlyduring the period in which this report is being prepared;  (b)  Designed such internal control over financial reporting, or causedsuch internal control over financial reporting to be designed under oursupervision, to provide reasonable assurance regarding the reliability offinancial reporting and the preparation of financial statements for externalpurposes in accordance with generally accepted accounting principles;  (c)  Evaluated the effectiveness of the registrant’s disclosure controlsand procedures and presented in this report our conclusions about theeffectiveness of the disclosure controls and procedures, as of the end of theperiod covered by this report based on such evaluation; and  (d)  Disclosed in this report any change in the registrant’s internalcontrol over financial reporting that occurred during the registrant’s most recentfiscal quarter (the registrant’s fourth fiscal quarter in the case of an annualreport) that has materially affected, or is reasonably likely to materiallyaffect, the registrant’s internal control over financial reporting; and
5.  The registrant’s other certifying officer(s) and I have disclosed, basedon our most recent evaluation of internal control over financial reporting, tothe registrant’s auditors and the audit committee of the registrant’s board ofdirectors (or persons performing the equivalent functions):
 (a)  All significant deficiencies and material weaknesses in thedesign or operation of internal control over financial reporting which arereasonably likely to adversely affect the registrant’s ability to record,process, summarize and report financial information; and  (b)  Any fraud, whether or not material, that involves managementor other employees who have a significant role in the registrant’s internalcontrol over financial reporting.   Date: May 11, 2005 /s/ KEVIN ARMSTRONG   Kevin Armstrong Chief Executive Officer