You should be able to use the content negotiation support on Crossref to get the metadata, which does include the ISSNs - or at least has the potential to if they are available. E.g. 

curl -LH "Accept: application/rdf+xml;q=0.5, application/vnd.citationstyles.csl+json;q=1.0" http://dx.doi.org/10.1126/science.169.3946.635

Gives 

{
  "subtitle": [],
  "subject": [
    "General"
  ],
  "issued": {
    "date-parts": [
      [
        1970,
        8,
        14
      ]
    ]
  },
  "score": 1.0,
  "prefix": "http://id.crossref.org/prefix/10.1126",
  "author": [
    {
      "family": "Frank",
      "given": "H. S."
    }
  ],
  "container-title": "Science",
  "page": "635-641",
  "deposited": {
    "date-parts": [
      [
        2011,
        6,
        27
      ]
    ],
    "timestamp": 1309132800000
  },
  "issue": "3946",
  "title": "The Structure of Ordinary Water: New data and interpretations are yielding new insights into this fascinating substance",
  "type": "journal-article",
  "DOI": "10.1126/science.169.3946.635",
  "ISSN": [
    "0036-8075",
    "1095-9203"
  ],
  "URL": "http://dx.doi.org/10.1126/science.169.3946.635",
  "source": "CrossRef",
  "publisher": "American Association for the Advancement of Science (AAAS)",
  "indexed": {
    "date-parts": [
      [
        2013,
        11,
        7
      ]
    ],
    "timestamp": 1383796678887
  },
  "volume": "169"
}


Owen Stephens
Owen Stephens Consulting
Web: http://www.ostephens.com
Email: [log in to unmask]
Telephone: 0121 288 6936

On 5 Mar 2014, at 12:30, Graham, Stephen <[log in to unmask]> wrote:

> OK, I've received a couple of emails telling me that the ISSN is not always included in the DOI - that it depends on the publisher. So, I guess my original question still stands!
> 
> Stephen
> 
> From: Graham, Stephen
> Sent: 05 March 2014 12:25
> To: [log in to unmask]
> Subject: RE: Retrieving ISSN using a DOI
> 
> Sorry - I've answered my own question. The ISSN is actually contained in the DOI. Didn't realise this! D'oh!
> 
> Stephen
> 
> From: Graham, Stephen
> Sent: 05 March 2014 12:14
> To: [log in to unmask]
> Subject: Retrieving ISSN using a DOI
> 
> Hi All - is there a service/API that will return the ISSN if I provide the DOI? I was hoping that the Crossref API would do this, but I can't see the ISSN in the JSON it returns.
> 
> I'm adding a DOI field to our OPAC ILL form, so if the user has the DOI they can use this to populate the form rather than add all the data manually. When the user submits the form I'm querying our openURL resolver API to see if we have access to the article. If we do then the form will alert the user and provide a link. The query to the openURL resolver works better if we have the ISSN, but if the user has used a DOI the ISSN is frustratingly never there.
> 
> Stephen
> 
> Stephen Graham
> Online Information Manager
> Information Collections and Services
> University of Hertfordshire, Hatfield.  AL10 9AB
> Tel. 01707 286111
> Email [log in to unmask]<mailto:[log in to unmask]>