Model: ProjectModel declared project id in model.
      public class ProjectModel
{
    public List<string> BusinessPriority { get; set; }
    public string projectId { get; set; }
    public string sSessionValue
    {
        get;
        set;
    }     
}
Index.html: index html code I will get autopopulate value in the below text box.but model property is null.
    <div class="col-md-2">
                            <div class="col-md-11">
                                <label class="control-label">Project Id</label>
                            </div>
                        </div>
                        <div class="col-md-2">
                            <div class="form-group form-group-md">
                                @Html.TextBoxFor(model => model.projectmodel.projectId, new { @class = "form-control", id = "ProjectId",@readonly = "true" })
                            </div>
                        </div>
Controller: Home Controller code below Session variables [HttpPost]
    public ActionResult Index(CommonModel data)
    {
        // Assign value into session
         Session["ProjectId"] = data.projectmodel.projectId;
        // Redirect view
        return RedirectToAction("Financials");
    }
    public ActionResult Financials()
    {
        // Create object of model call for call properties and set value
        var vSessionValue = new CommonModel();
       // Session["ProjectId"] = Request["ProjectId"].ToString();
        try
        {
            // check existing value into session
            if ((Object)Session["ProjectId"] != null)
                // assign value into properties
                vSessionValue.projectmodel.sSessionValue =  Session["ProjectId"].ToString();
            else
                // if session expired than set custom message
                vSessionValue.projectmodel.sSessionValue = "Session Expired";
        }
        catch
        {
        }
        // return value to view
        return View(vSessionValue);
    }
